Comparison of concrete rheometers:

International tests at LCPC

(Nantes, France)

in October, 2000

Editors:

 Chiara F. Ferraris, Lynn E. Brower

Authors (alphabetical order):

Phil Banfill, Denis Beaupré,

Frédéric Chapdelaine, François de Larrard,

Peter Domone, Laurent Nachbaur,

Thierry Sedran, Olaf Wallevik,

Jon E. Wallevik

NISTIR 6819
NISTIR 6819

Comparison of concrete rheometers:

International tests at LCPC

(Nantes, France)

in October, 2000

Editors:

Chiara F. Ferraris, National Institute of Standards and Technology (USA)

Lynn E. Brower, Master Builders Technologies (USA)

Authors (in alphabetical order):

Phil Banfill, Heriot-Watt Univ., (UK)

Denis Beaupré, Laval Univ., (Canada)

Frédéric Chapdelaine , Laval Univ (Canada)

François de Larrard, Laboratoire Central des Ponts et Chaussées, (France)

Peter Domone , University College London (UK)

Laurent Nachbaur, Laboratoire Central des Ponts et Chaussées, (France)

Thierry Sedran, Laboratoire Central des Ponts et Chaussées, (France)

Olaf Wallevik, The Icelandic Building Research Institute, (Iceland)

Jon E. Wallevik, Norwegian Univ. of Science and Technology, (Norway)

September 2001

U.S. Department of Commerce

Donald L. Evans, Secretary

National Institute of Standards and Technology

Karen H. Brown, Acting Director
Disclaimer

Commercial equipment, instruments, and materials mentioned in this

paper are identified to foster understanding. Such identification does not

imply recommendation or endorsement by the National Institute of

Standards and Technology (NIST), nor does it imply that the materials or

equipment identified are necessarily the best available for the purpose.

During the trial in France, on October 2000, to ensure proper use,

each designer operated his instrument and described its operation in this

report. All data were immediately, after each test, collected in electronic

form on specially labeled diskettes for later analysis.

The role of NIST was to coordinate and foster the rheometer study.

Dr. Chiara Ferraris is the chair of ACI 236A, “Workability of Fresh

Concrete”, and in this role she organized the tests and edited the report. She

is not one of the authors, but only an editor. Lynn Brower, co-editor, is the

secretary of ACI 236A.

The opinions expressed in this report are not endorsed by NIST

and they reflect only the opinion of the authors.
Preparation of the report

Editors

Chiara F. Ferraris, National Institute of Standards and Technology, Gaithersburg (USA)

Lynn Brower, Master Builders, Inc., Cleveland OH (USA)

Authors (alphabetical order)

Phil Banfill, Heriot-Watt Univ., Edinburgh (UK)

Denis Beaupré, Laval Univ., Quebec (Canada)

Frédéric Chapdelaine , Laval Univ., Quebec (Canada)

François de Larrard, Laboratoire Central des Ponts et Chaussées, Nantes (France)

Peter Domone , University College London (UK)

Laurent Nachbaur, Laboratoire Central des Ponts et Chaussées, Paris (France)

Thierry Sedran, Laboratoire Central des Ponts et Chaussées, Nantes (France)

Olaf Wallevik, The Icelandic Building Research Institute, Reykjavik (Iceland)

Jon E. Wallevik, Norwegian Univ. of Science and Technology, Trondheim (Norway)

Contact

Chiara F. Ferraris

NIST

100 Bureau drive, MS 8621, Gaithersburg MD 20899 (USA)

Phone: +301-975 6711 Fax: +301-990 6891

E-mail: clarissa@nist.gov
Participants in the tests at LCPC, Nantes (France)

1

st row: left to right

Jean-Yves Petit, Jinhua Jin, Jon Wallevik, Daniel Michel , Francois de Larrard, Chiara

Ferraris, Olafur Wallevik, Marie-Andrée Gilbert, Thierry Sedran, Frederic Chapdelaine,

Mohammed Sonebi, Joseph Daczko

2

nd Row: left to right

Alain Doucet, Michel Dauvergne, Pierre Chelet (behind Michel), Bernard Dehousse, Phil

Banfill, Peter Domone, Andreas Griesser, Laurent Nachbaur, Erik Nordenswan

On top of the CEMAGREF-IMG:

Denis Beaupré

Affiliations of participants (in alphabetical order):

Addtek, Parainen (Finland): Erik Nordenswan

Advanced Concrete and Masonry Centre , Paisley (UK): Mohammed Sonebi

Heriot-Watt Univ., Edinburgh (UK): Phil Banfill, Jinhua Jin

The Icelandic Building Research Institute, Reykjavik (Iceland): Olaf Wallevik

Laboratoire Central des Ponts et Chaussées, Nantes (France): François de Larrard,

Thierry Sedran, Alain Doucet, Michel Dauvergne, Pierre Chelet, Bernard Dehousse,

Daniel Michel

Laboratoire Central des Ponts et Chaussées, Paris (France): Laurent Nachbaur

Laval Univ., Quebec (Canada): Denis Beaupré, Frédéric Chapdelaine, Marie-Andrée

Gilbert

National Institute of Standards and Technology, Gaithersburg (USA): Chiara F.

Ferraris

Norwegian Univ. of Science and Technology, Trondheim (Norway): Jon E. Wallevik

Univ. d’Artois, Bethune (France): Jean-Yves Petit

University College London (UK): Peter Domone

Master Builders, Inc., Cleveland OH (USA): Joseph Daczko

Swiss Federal Institute of Technology, Zürich (Switzerland): Andreas Griesser
Foreword

The American Concrete Institute (ACI) sub-committee 236A, “Workability of

Fresh Concrete,” immediately was faced, upon its creation in fall 1999, with how to

determine appropriate methods to measure concrete workability. The material sciencebased approach to measure workability would be to use a concrete rheometer. There are

several rheometers used around the world that have significant design differences, but no

standard method with which to compare their results. ACI 236A members determined

that, as no reference material was available, one method to compare the rheometers would

be to test them under the same conditions using the same concretes. Some tentative

analysis made to compare two rheometers was performed in the past [1, 2] but did not

involve most of the available rheometer designs.

ACI 236A drafted a plan for comparing the five types of rheometers available and

requested funds from the Concrete Research Council (CRC) of ACI and from industry to

support this work. CRC granted funds in 2000 and the first trial was scheduled for

October, 2000. It was held at the Laboratoire Central des Ponts et Chaussées (LCPC)

facility in Nantes, France on October 23-27, 2000. The rheometers selected included all

commercially available concrete rheometers (four), to the best knowledge of the ACI

236A committee members, and one coaxial concrete rheometer developed for research.

The authors of this report are principal investigators who participated in the first

trial and contributed to the report. This report describes the tests performed and the results

obtained. It was not published as an ACI document and therefore was not submitted to the

Technical Activities Committee (TAC) for approval. There are two reasons for this not

being an ACI document: 1) ACI documents are guidelines and practice recommendations,

not research reports; 2) all ACI reports are consensus documents balloted and approved by

the members of a committee, while this report only reflects the views and opinions of the

authors. All members of ACI 236A were invited to review the document prior to

publication (as shown in the acknowledgements). It was also discussed during the regular

meetings of ACI 236A at the ACI spring 2001 convention in Philadelphia (PA).
Acknowledgements

This project could not have been possible without the financial support of the ACI

Concrete Research Council. Its support offset the cost of the transportation of the

rheometers from Canada, Switzerland, UK, and Grenoble (France) to the test site at

Laboratoire Central des Ponts et Chaussées (LCPC) in Nantes (France). We are thankful

for the hospitality and the professionalism of the staff of LCPC, who welcomed the

international team for the week-long tests. We would like to acknowledge the

participation of LCPC staff, in particular: Michel Dauvergne, Daniel Michel, Alain

Doucet, Pierre Chelet, Bernard Dehousse, David Chopin and Bernard Guieysse. They

prepared and tested all the concrete used for this project, and conducted all the concrete

quality control measurements.

We would also like to thank all the participants and their organizations for their

involvement in the planning and execution of this comparison. Their names are listed in

the participants list placed before the foreword. Also, Master Builders Technology (MBT)

should be thanked for providing their expertise to administer the funds provided by CRC.

The authors would also like to thank all the reviewers for their efforts in reading this

rather large report (in alphabetical order): Emmanuel Attiogbe (MBT), Samir Chidiac

(McMaster Univ.), Geoffrey Fronhsdorff (NIST), Edward Garboczi (NIST), Aulis Kappi

(Addtek R&D), Nicos Martys (NIST), Abdelbaki Mekhatria (CRIB, Laval Univ.), Della

Roy (Penn State Univ.), Leslie Struble (ACBM, Univ. of Illinois), Kejin Wang (Iowa

State Univ.), and Walter Rossiter (NIST). We would also like to thank the members of

ACI 236A for their lively discussion during the Spring 2001 meeting and their support of

this study.
Table of Contents

1. INTRODUCTION.................................................................................................................................................1

2. CONCRETE MIXTURES USED IN TESTS AT NANTES ......................................................................3

2.1. CONSTITUENTS...................................................................................................................................................3

2.2. MIXTURE PROPORTIONS....................................................................................................................................4

2.3. CONCRETE PRODUCTION...................................................................................................................................4

2.4. FRESH CONCRETE ANALYSES............................................................................................................................7

3. CONCRETE RHEOMETERS....................................................................................................................... 11

3.1. THE BML RHEOMETER...................................................................................................................................11

3.1.1. Description of apparatus.................................................................................................................... 11

3.1.2. Test procedures.................................................................................................................................... 14

3.1.3. Calibration ............................................................................................................................................ 17

3.2. THE BTRHEOM RHEOMETER.......................................................................................................................19

3.2.1. Description of the apparatus............................................................................................................. 19

3.2.2. Test procedure...................................................................................................................................... 19

3.2.3. Analysis of the data ............................................................................................................................. 20

3.3. THE CEMAGREF-IMG RHEOMETER..........................................................................................................22

3.3.1. Description of the apparatus............................................................................................................. 22

3.3.2. Test procedure...................................................................................................................................... 25

3.3.3. Analysis of the data ............................................................................................................................. 25

3.4. THE IBB RHEOMETER......................................................................................................................................30

3.4.1. Description of the apparatus............................................................................................................. 30

3.4.2. Analysis of the data ............................................................................................................................. 31

3.5. THE TWO-POINT RHEOMETER........................................................................................................................33

3.5.1. Description of the apparatus............................................................................................................. 33

3.5.2. Test procedure...................................................................................................................................... 34

3.5.3. Analysis of the data ............................................................................................................................. 36

4. RESULTS ............................................................................................................................................................. 37

4.1. QUALITY CONTROL MEASUREMENTS: SLUMP , MODIFIED SLUMP , DENSITY............................................37

4.2. COMPARISON BETWEEN RHEOMETERS..........................................................................................................39

4.2.1. Comparison with the slump and modified slump test .................................................................... 39

4.2.2. Variation of the values by concrete composition ........................................................................... 41

4.2.2.1. Analysis of variation of the yield stress and plastic viscosity by mixture..........................................41

4.2.3. Relative rank of the data by each rheometer................................................................................... 43

4.2.4. Graphical comparison of pairs of rheometer results..................................................................... 44

4.2.5. Correlation functions and coefficients between pairs of rheometers.......................................... 45

5. DISCUSSION...................................................................................................................................................... 60

5.1. COMMENTS ON CORRELATIONS BETWEEN PAIRS OF RHEOMETERS...........................................................60

5.1.1. Linear regression or not? ................................................................................................................... 60

5.1.2. Critical review of R.............................................................................................................................. 60

5.2. DISCUSSION ON DISCREPANCIES ON ABSOLUTE VALUES............................................................................61

5.3. CORRELATION BETWEEN THE SLUMP AND THE YIELD STRESS ...................................................................62

6. SUMMARY OF FINDINGS ........................................................................................................................... 64

7. FUTURE WORK............................................................................................................................................... 65

8. REFERENCES ................................................................................................................................................... 66

APPENDIXES .......................................................................................................A-69
List of Figures

Figure 1: Size distributions of the aggregates used .....................................................................................................3

Figure 2: The ConTec viscometers: a) Version 3; b) Version 4.............................................................................11

Figure 3: Output from the FreshWin software: A) The menu-driven window used to change relevant

parameters; B) The basic output of a test result...............................................................................................12

Figure 4: The inner and outer cylinder of the BML Viscometer 3 (or BML rheometer hereafter). ..................12

Figure 5: The assembly of inner cylinder of the BML viscometer 3. This figure shows the sequence for

installing the inner cylinder. ................................................................................................................................13

Figure 6: A top view of a coaxial cylinder rheometer. The outer cylinder (radius 

o

r ) rotates at angular

velocitywo, while the inner cylinder (radius ir ) is stationary and registers the torque transferred

through the fluid material.....................................................................................................................................15

Figure 7: The relation between torque measured by the rheometer and shear stress...........................................17

Figure 8: Output from the software during calibration of the BML rheometer...................................................18

Figure 9: Principle of the BTRHEOM rheometer......................................................................................................19

Figure 10: The BTRHEOM rheometer showing the blades at the top and bottom of the bucket containing the

concrete...................................................................................................................................................................21

Figure 11: Schematic of the CEMAGREF-IMG rheometer.....................................................................................22

Figure 12: Picture of the CEMAGREF-IMG rheometer...........................................................................................23

Figure 13: Top view of the CEMAGREF-IMG rheometer with grid on the inner cylinder and blades on the

outer one.................................................................................................................................................................23

Figure 14: Sketch showing set-up of the calibrated load cells to measure the torque.........................................24

Figure 15: Description of the speed-meter..................................................................................................................25

Figure 16: Diagram of plug flow phenomenon ..........................................................................................................26

Figure 17: Typical curves versus time obtained during a test..................................................................................29

Figure 18: Torque-rotation speed curve for the same test as in Figure 17.............................................................29

Figure 19: The IBB Rheometer.....................................................................................................................................30

Figure 20: Details of the H-shaped impellers, bowls and planetary motion for IBB rheometer for concrete (a)

and mortar (b) . Dimension in mm.....................................................................................................................31

Figure 21: Example of calculation with indication of the meaning of the parameters. Y= speed; x = Torque

..................................................................................................................................................................................32

Figure 22: Impeller and bowl dimensions (in mm)....................................................................................................33

Figure 23: The overall arrangement of the Two-Point test apparatus...................................................................34

Figure 24: Comparison of the slumps measured by the standard method and the modified method. The

dotted line represents the 45 ° line. ....................................................................................................................37

Figure 25: Comparison of standard slump and yield stress as measured with the five rheometers. The second

axis in N⋅m gives the results obtained with the IBB. ......................................................................................40

Figure 26: Comparison of plastic viscosity calculated from the modified slump test and plastic viscosity as

measured with the five rheometers. The second axis in N⋅m⋅s gives the results obtained with the IBB.

..................................................................................................................................................................................41

Figure 27: Comparison of the yield stresses as measured with the rheometers....................................................42

Figure 28: Comparison of the plastic viscosities as measured with the rheometers ............................................42

Figure 29: Comparison between BML and BTRHEOM...........................................................................................48

Figure 30: Comparison between BML and CEMAGREF-IMG..............................................................................49

Figure 31: Comparison between BML and IBB.........................................................................................................50

Figure 32: Comparison between BML and Two-Point test......................................................................................51

Figure 33: Comparison between BTRHEOM and CEMAGREF-IMG..................................................................52

Figure 34: Comparison between BTHEOM and IBB................................................................................................53

Figure 35: Comparison between BTRHEOM and Two-Point test.........................................................................54

Figure 36: Comparison between IBB and CEMAGREF-IMG................................................................................55

Figure 37: Comparison between CEMAGREF-IMG and Two-Point test.............................................................56

Figure 38: Comparison between IBB and Two-Point test........................................................................................57

Figure 39: Comparison of plastic viscosities between BML, BTRHEOM and Two-Point test when the data

points from Mixture #4 were omitted................................................................................................................58
Figure 40: Comparison of plastic viscosities between IBB and Two-Point test. The data from Mixture #4

were omitted...........................................................................................................................................................59

Figure 41: Comparison of measured and predicted yield stress according to equations developed by Hu and

Kurakawa ................................................................................................................................................................63

List of Tables

Table 1: Compositions of mixtures (in kg/m3) produced with crushed 5/16 mm coarse aggregate in the

mixing plant during the rheology week...............................................................................................................6

Table 2: Compositions of mixtures (in kg/m3) produced with rounded 4/20 mm coarse aggregate on the

mixing plant during the rheology week...............................................................................................................6

Table 3: Composition of a mixture (in kg/m3) produced with crushed 0/6.3 mm coarse aggregate in the

mixing plant during the rheology week...............................................................................................................7

Table 4: Fresh concrete analyses. Mixtures # 1-4. .......................................................................................................8

Table 5: Fresh concrete analyses. Mixtures # 5-7 & 12..............................................................................................9

Table 6: Fresh concrete analyses. Mixtures # 8-11....................................................................................................10

Table 7: Dimensions of the inner and outer cylinders of the five standard measuring systems. The

configuration used in the tests presented here is highlighted in gray...........................................................12

Table 8: Slump Measurements......................................................................................................................................38

Table 9: Yield stress and viscosities calculated from the measurements...............................................................39

Table 10: Ranking of the yield stresses of the mixtures as determined by the rheometers and the slump. The

mixtures are ranked in decreasing order of yield stress from 1 to 12. The higher the slump, the lower

the yield stress.......................................................................................................................................................44

Table 11: Ranking of the plastic viscosity of the mixtures as determined by the rheometers. The mixtures are

ranked in decreasing order of plastic viscosities from 1 to 12.......................................................................44

Table 12: Correlation coefficients for yield stress.....................................................................................................46

Table 13: Correlation coefficients for plastic viscosity ............................................................................................46

Table 14: Correlation coefficients for plastic viscosity if Mixture #4 for Two-Point test is not considered

(see text for rationale)...........................................................................................................................................46

Table 15: Between-rheometer linear correlation functions for the yield stress. The rheometers in the column

head are Y and those in the row head are X. In each cell the coefficients of the equation Y=AX +B are

shown. The rheometers are listed in alphabetical order..................................................................................47

Table 16: Between-rheometer linear correlation functions for the plastic viscosity (all data available are

used). The rheometers in the column head are Y and those in the row head are X. In each cell the

coefficients of the equation Y=AX +B are shown. The rheometers are listed in alphabetical order......47

Table 17 Critical values for the correlation coefficient R of a sample extracted from a normal distributed

population. α is the probability, and ν = n-2, n being the number of points. If the calculated value of R

is higher than the reference value shown in the table, there is a probability α that X and Y are

dependent...............................................................................................................................................................61
1

1. Introduction

Concrete is a complex material and its properties in the fresh state can have a large effect

on hardened properties. Unfortunately, the technology to measure the properties of fresh

concrete has not changed significantly in the last century. The main fresh concrete

property, workability, is still measured using the slump test (ASTM C 143). In fact,

concretes with the same slump may flow differently and have different workability [3, 4].

The reason two concretes with the same slump behave differently during placement is

that concrete flow cannot be defined by a single parameter. Most researchers agree that

the flow of concrete can be described reasonably well using a Bingham equation. This

equation is a linear function of the shear stress (the concrete response) versus shear rate.

Two parameters provided by the Bingham equation are the yield stress and the plastic

viscosity. The yield stress correlates reasonably well with the slump value, but the plastic

viscosity is not measured at all using the slump test. Plastic viscosity governs concrete

flow behavior after flow has started, i.e., after the yield stress is overcome. The existence

of the plastic viscosity helps explain why concretes with the same slump may behave

differently during placement.

It is critical to completely define concrete flow when special concretes, demanding major

control of workability, such as a self-compacting concrete (SCC) or high performance

concrete (HPC), are used or when concrete is placed in highly-reinforced structures [5].

This is critical because a single parameter such as the slump does not adequately describe

their behavior during placement. More sophisticated and precise tools are needed to

determine the workability or flow properties of such concretes. Several instruments have

been designed to address this problem [6], some in an empirical manner, and some

attempting to apply absolute physical measurements to concrete rheology, i.e., fluid

rheology. The devices attempting to use fluid rheology methods to measure the flow of

concrete, i.e., measuring shear stress at varying shear rates, are called rheometers [7].

They all measure the resistance to flow of concrete at varying shear rate conditions.

Rheometers designed for polymers or neat fluids with no solid particles are not suitable

for measuring concrete due to the presence and size of the solid aggregates. This situation

has lead to a wide variety of designs for concrete rheometers, making it difficult if not

impossible to compare the results of the rheometers on a common basis. One obvious

solution would be to have a standard reference material to calibrate the rheometers. No

such standard material has been developed to simulate fresh concrete behavior.

Therefore, the best alternative was to conduct measurements using the rheometers on the

same concrete mixtures. The first project goal was to compare the data measured by the

various devices. If these measurements differed significantly, the second goal was to

establish correlation functions between the rheometer results to make possible reasonable

comparisons of data obtained with different rheometers.

The concrete rheometers that are available today and were used in this study are:

• BML (Iceland) [8, 9]

• BTRHEOM (France) [10, 11]

• CEMAGREF-IMG coaxial rheometer (France) [1]
2

• IBB (Canada) [12]

• Two-Point (UK) [13]

The IBB and Two-Point rheometers are based on rotating an impeller in fresh concrete

contained within a cylindrical vessel. The shape of the vane varies with the rheometer.

The speed of rotation of the blade is increased and then decreased while the concrete

resistance or torque is measured. The BTRHEOM is a parallel plate rheometer. The

concrete is placed in a cylindrical container with a fixed bottom plate. A top plate

embedded in the concrete is rotated at increasing and then decreasing speeds and the

torque is measured. The CEMAGREF-IMG and the BML are coaxial cylinder rheometers

in which one cylinder (inner cylinder for the CEMAGREF-IMG and outer for the BML)

is rotated at increasing and decreasing speed and the torque induced by the concrete on

the inner cylinder is measured. The flow pattern of the concrete in the IBB and TwoPoint rheometers cannot be easily assessed or modeled, while the flow can be

mathematically modeled for the coaxial rheometers (BML, CEMAGREF-IMG) and for

the parallel-plate rheometer (BTRHEOM). For these three rheometers (BML,

BTRHEOM, CEMAGREF-IMG), rheological characteristics in fundamental units can be

calculated. The Two-Point test rheometer requires indirect methods using calibrating

fluids of known viscosity to convert quantitative data into the fundamental units needed.

On the other hand, the IBB is not calibrated with a fluid and therefore, the results are not

reported in fundamental units. The aim of the present project was to compare

measurements from these five rheometers to provide data to establish correlations among

them. Differences between the various rheometers were expected, due to the complex

granular structure of concrete. Slip at the rheometer surfaces and coarse particle

segregation are just two examples of such granular aspects of fresh concrete behavior.

They are not accounted for in rheometer analyses, that are based upon classical fluid

mechanics of homogeneous fluids.

Comparison and correlation functions, which can relate the results obtained with the

various rheometers, are essential to advance the science of concrete rheology and

therefore provide a better characterization of concrete “workability”.

Under the auspices of ACI sub-Committee 236A, “Workability of Fresh Concrete,” a

group of researchers obtained a grant from ACI’s Concrete Research Council (CRC) to

conduct a series of comparison tests on concrete rheometers. The first test was conducted

on October 23-27, 2000 in the facilities of the Laboratoire Central des Ponts et Chaussées

(LCPC) located in Nantes (France).

This report describes the rheometers used and their operation, the concrete compositions

and preparation procedure, and all the data obtained as well as some data interpretation of

this. All the data are presented as measured. This will provide a valuable database for use

by researchers in this field. Summaries of the different aspects of this research along with

further analysis, will be presented in ACI journals and other publications.
3

2. Concrete Mixtures Used in Tests at Nantes

2.1. Constituents

Twelve mixtures were produced with local materials from the Nantes area.

The cement was a CPA CEM I 52.5 from Saint-Pierre la Cour (equivalent to an ASTM

type I). For the self-compacting mixtures, a “Piketty” limestone filler was added. A

densified silica fume from Anglefort was used in some concretes for which both low

yield stress and low plastic viscosity was required. Most mixtures used a high-range

water reducer (HRWRA), which was either a polycarboxylate (commercial name: “MBT

Glenium 27”) or a sulphonated melamine (Commercial name: “Chryso Résine GT”). A

viscosity agent (Commercial name: “ MBT Meyco MS685”, a suspension of amorphous

precipitated nanosilica) was added to the self-compacting mixtures. Tap water was used

for all mixtures.

Up to four different aggregate fractions were used for each concrete, to obtain the best

possible control of the aggregate size distribution. All concretes contained the same sand,

a 0/4 (from 0 mm to 4 mm) Estuaire sand (from the Loire river). In addition, some

mixtures also used a very fine (correcting) sand called 0/0.4 from Palvado, to maintain a

continuous distribution between the cement and the aggregate size ranges.

Mixtures #1-7 were made with two fractions of crushed coarse aggregate (gneiss from the

Pontreaux quarry, with a maximum size of 16 mm). Mixtures # 8-11 contained a rounded

silico-calcareous river gravel (also in two fractions) from Longué (Vienne river), with a

maximum size of 20 mm. Finally, the last mixture #12 only contained a “small” crushed

aggregate from Pontreaux with a maximum size of 6.3 mm. Size distributions of all

agregates are displayed in Figure 1.

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

100

-3 -2 -1 0 1

d (mm)

% passing

Limestone Filler

Portland Cement

Palvado 0/0.4

Estuaire 0/4

Pontreaux 2/6.3

Longué 4/10

Pontreaux 5/12.5

Pontreaux 10/16

Longué 10/20

0.001 0.01 0.1 1 10

Figure 1: Size distributions of the aggregates used
4

2.2. Mixture proportions

The mixtures were designed with the help of LCPC mixture-design software BétonlabPro

2 [14]. The objective was to obtain a broad range of combinations of yield stress and

plastic viscosity, while minimizing the tendency to segregation. This strategy was

followed for #1-4 and #8-11 mixtures. The main difference between these two series was

the nature of the coarse aggregate. Since the goal of this rheology project was to test the

correlation between a variety of devices, it was useful to see whether such correlations

would hold for different types of aggregate. Repetitions of mixtures were planned if time

allowed.

Mixture #5 was a gap-graded mixture, with the high coarse/fine aggregate ratio slightly

higher than most mix-design method recommendations. The idea was to generate a

concrete in which mortar and coarse aggregate would have a tendency to separate from

each other, but would not display any obvious segregation in the normal operations of

mixing, discharging and casting.

Mixtures #6-7 were planned to be self-compacting mixtures, with very low yield stress,

moderate plastic viscosity and high stability at rest and during casting in congested areas.

Both mixtures had the same “dry” composition, differing only in the water and

superplasticizer dosages.

Finally, mixture # 12 was a high-performance micro-concrete made with a very small

aggregate (having a maximum size of 6.3 mm), with a high amount of fines, a low yield

stress and a moderate plastic viscosity. Although the test of this concrete was not

originally intended, it was considered interesting to include it, because this mixture was

designed to minimize the wall effects and segregation in the various rheometers.

Before the testing date, all mixtures were prepared and adjusted in the laboratory, on the

basis of 40 L batches produced with a 120 L pan mixer.

2.3. Concrete production

Between development of the mixtures in the laboratory and production at the concrete

plant, the cement silo was filled with a new delivery of portland cement (from the same

manufacturer). Also, the various aggregate fractions were stored outside, so that

aggregate water content varied widely during the project.

Concretes were produced at the Mixing Study Station of LCPC, Nantes (see figure in

Appendix A). This station is devoted to research on the production of granular cold

material (like concrete and various road base materials) on an industrial scale. A variety

of mixers can be mounted on the station, which incorporates all ordinary facilities for

storing, weighing and batching materials with suitable automation. For this project, a

1 m3 pan-mixer was used.

In order to control the water content of the concretes, the sand fractions were first

weighed and batched into the mixer. The sand fractions could contribute the largest error
5

in the water content of the concrete. After some minutes of mixing, a sample of the sand

was taken to measure the water content. Then, the masses to be added in order to control

the proportions of the mixture were calculated, and all the other materials were batched,

including coarse aggregate fractions, cement and other binders if any, and finally the rest

of water incorporating one third of the total superplasticizer amount. The rest of the

superplasticizer was added later as needed.

Due to changes in material batches, sand water content, and batch size, the workability of

the concretes often differed from that originally obtained in the lab. In order to avoid

production of unsuitable mixtures, the mixing process was systematically interrupted, and

the concrete sampled to make a slump test. Based on this slump indication,

supplementary additions of water and/or superplasticizer were made as needed. Then

mixing was restarted and stopped after a while to check whether the slump was

acceptable or not. Concretes were generally accepted after a number of corrections

ranging from 0 to 3 (depending on the mixture) but, as the scope of the program was to

compare the different rheometers on the same mixtures whatever they were, the variety of

mixing procedures was not a problem.

Each concrete mixture was then discharged on a conveyor belt and first poured into a

500 L bucket used to feed the CEMAGREF-IMG rheometer (see picture in Appendix A),

and then into a smaller bucket for the other rheometers. During the operation of the

conveyor belt, automatic sampling of fresh concrete was performed with a mechanical

sampler [15]. The aim of this sampling was to check that no segregation took place

during discharge, which would have created an artifact by leading to different mean

compositions in the various rheometers (see Section 0 for a description of the

methodology and the results).

Then the buckets were transported to the laboratory. The larger bucket was discharged

into the CEMAGREF-IMG rheometer, and the small one was offered to the participants.

Each team filled its rheometer by hand scooping from the small bucket. During this stage,

an operator was continuously agitating the mixture to avoid any significant segregation in

the small bucket. The specific gravity of the fresh concrete was determined with a 5 L

specimen. Based upon this measurement, the real composition of mixtures per unit

volume could be calculated. Mixture compositions appear in Table 1, Table 2 and Table

3.
6

Table 1: Compositions of mixtures (in kg/m3) produced with crushed 5/16 mm

coarse aggregate in the mixing plant during the rheology week.

Mixture No. 1 2 3 4 5* 6** 7**

Pontreaux 10/16 368 482 620 456 1161 780 768

Pontreaux 5/12.5 588 405 356 458 - 175 173

Estuaire 0/4 763 804 440 783 661 773 762

Palvado 0/0.4 - - - 56 - 52 52

Cement from St Pierre la Cour 494 426 723 419 391 314 310

Piketty limestone filler - - - - - 135 133

Anglefort silica fume - 21.3 - - - - -

Glenium 27 SP (in bold: Chryso

GT SP)

6.294 6.722 11.403 0.000 1.590 13.837 10.175

Viscosifier agent - - - - - 8.171 8.059

Water 188 216 222 201 194 175 184

Target yield stress high low low high mod. very low very low

Target plastic viscosity high low high low mod. low low

Notes: *: gap-graded mixture. **: attempt to a self-compacting mixtures

Table 2: Compositions of mixtures (in kg/m3) produced with rounded 4/20 mm

coarse aggregate on the mixing plant during the rheology week.

Mixture No. 8 9 10 11

Longué 10/20 563 461 600 550

Longué 4/10 363 394 349 317

Estuaire 0/4 739 797 438 743

Palvado 0/0.04 - - - 53

OPC from St Pierre la Cour 480 422 725 398

Anglefort Silica fume - 21.1 - -

Glenium 27

Superplasticizer

6.414 5.316 7.608 1.164

Water 205 218 225 213

Target yield stress high low low high

Target plastic viscosity high low high low
7

Table 3: Composition of a mixture (in kg/m3) produced with crushed 0/6.3 mm

coarse aggregate in the mixing plant during the rheology week

Mixture No. 12

Pontreaux 2/6.3 825

Estuaire 0/4 564

Cement from St Pierre la

Cour

613

Piketty limestone filler 107

Glenium 27

superplasticizer

10.215

Water 230

Target yield stress Low

Target plastic viscosity Moderate

2.4. Fresh concrete analyses

The results of the fresh concrete analyses are given in Table 4, Table 5, and Table 6. For

each mixture, eight samples were taken. Five corresponded with the concrete discharged

into the large bucket for the CEMAGREF-IMG rheometer and the remaining three

corresponded to the small bucket reserved for the laboratory rheometers. For each

sample, the paste content was determined by weighing the raw sample, then subtracting

the mass of dry aggregate obtained after washing on a 80 μm sieve and drying in a

microwave oven. The size distribution was then determined by sieving the particles less

than 2 mm and with a dedicated optical apparatus [15] for coarser particles. The results in

terms of the percentages of the various fractions are displayed in the tables.

For each concrete and each size fraction, the mean value and standard deviation were

calculated on the 8-sample series on one hand, and on the 5-sample and 3-sample subpopulations on the other hand. Looking at the overall standard deviations, it can be noted

that the concretes were quite homogeneous. The highest standard deviation on paste

percentage for any concrete was 0.98 % for Mixture # 10. In absolute terms, it appears

that the cement content variation of the samples was 18 kg/m3, a quite limited value.

It is important to judge whether differences in composition found between the concrete

for the large rheometer and the rest of the batch were significant. From the results of

statistical tests, it seems that a significant difference was found for four mixtures.

However, still focusing on the paste content, the highest difference found between the

mean values of the two populations is for Mixture # 8. Here, the mean paste contents for

the large rheometer concrete and for the rest of the batch were 28.7 % and 29.4 %,

respectively. The corresponding cement contents were from 480 kg/m3 to 492 kg/m3. By

performing a simulation with the BétonlabPro 2 software [14], and assuming a constant

water/cement ratio, it appears that the corresponding variation in slump was about 7 mm,

which is not significant. It can be concluded, therefore, that the mixtures were essentially

homogeneous. No significant segregation occurred during the discharge of concrete

batches, which could have created a bias in the rheometer comparison.
8

Table 4: Fresh concrete analyses. Mixtures # 1-4.

The unshaded rows give the results of the concrete used for the CEMAGREF-IMG rheometer, while the shaded areas are for

the other rheometers.

% of paste by mass

fraction

% of 0.08/2 fraction % of 2/10 fraction % of 10/D fraction

Nominal Values 28.6 28.4 40.3 26.2

Mixtures # 1 # 2 # 3 # 4 # 1 # 2 # 3 # 4 # 1 # 2 # 3 # 4 # 1 # 2 # 3 # 4

1 28.8 25.1 38.1 26.9 35.3 31.2 22.7 38.6 32.5 25.9 21.9 27.0 32.2 42.9 55.4 34.4

2 29.2 25.7 38.0 26.4 35.7 32.0 22.5 36.9 30.9 26.5 23.9 25.8 33.3 41.5 53.6 37.2

3 29.2 26.2 39.0 26.4 35.3 31.6 23.8 37.9 30.1 24.3 25.1 26.4 34.5 44.1 51.2 35.7

4 28.9 25.2 38.6 27.2 34.5 30.2 23.0 38.1 27.9 25.4 25.1 26.7 37.5 44.4 51.9 35.2

5 29.5 25.4 38.6 26.5 36.1 31.1 23.1 37.4 33.5 24.3 26.0 25.7 30.4 44.6 50.9 36.9

Mean value 29.1 25.5 38.5 26.7 35.4 31.2 23.0 37.8 31.0 25.3 24.4 26.3 33.6 43.5 52.6 35.9

Standard

deviation

0.26 0.44 0.41 0.36 0.60 0.69 0.51 0.65 2.14 0.98 1.58 0.57 2.67 1.28 1.91 1.20

6 28.3 25.9 39.0 26.4 34.3 32.0 23.7 37.5 33.3 28.6 25.4 27.8 32.4 39.3 50.8 34.7

7 29.3 25.8 38.3 26.2 36.0 32.0 22.9 36.7 31.4 26.0 25.4 26.0 32.6 42.0 51.7 37.3

8 29.3 25.4 37.9 26 33.9 30.6 22.7 36.1 31.9 27.9 23.64

3

24.1 34.2 41.4 53.68

6

39.8

Mean value 29.0 25.7 38.4 26.2 34.7 31.6 23.1 36.8 32.2 27.5 24.8 26.0 33.1 40.9 52.1 37.3

Standard

deviation

0.56 0.26 0.56 0.20 1.10 0.78 0.56 0.69 0.98 1.34 1.03 1.83 0.97 1.38 1.47 2.52

ALL SAMPLES

Mean value 29.1 25.6 38.4 26.5 35.2 31.4 23.0 37.4 31.4 26.1 24.5 26.2 33.4 42.5 52.4 36.4

Standard

deviation

0.37 0.38 0.43 0.38 0.82 0.69 0.49 0.81 1.80 1.55 1.34 1.09 2.10 1.81 1.67 1.77
9

Table 5: Fresh concrete analyses. Mixtures # 5-7 & 12.

The unshaded rows give the results of the concrete used for the CEMAGREF-IMG rheometer, while the shaded areas are for

the other rheometers.

% of paste by mass fraction % of 0.08/2 fraction % of 2/10 fraction % of 10/D fraction

Nominal values 24.3 26.5 26.7 40.7

Mixtures # 5 # 6 # 7 # 12 # 5 # 6 # 7 # 12 # 5 # 6 # 7 # 12 # 5 # 6 # 7

1 25.1 26.2 25.3 40.8 26.8 34.3 32.9 34.7 9.5 16.6 13.4 65.3 63.8 49.1 53.6

2 25.5 26 26.3 40.5 26.3 33.4 34.5 34.1 9.8 14.7 16.1 65.9 63.9 51.9 49.4

3 25.0 26.7 26.3 40.1 26.3 35.1 34.8 34.3 9.8 14.7 14.7 65.7 63.9 50.2 50.5

4 25.2 26.3 26.1 41 26.3 33.6 34.0 34.1 10.9 15.8 13.6 65.9 62.7 50.7 52.5

5 25.3 27 25.6 40.2 26.8 35.2 33.4 33.6 10.0 16.6 13.1 66.4 63.1 48.2 53.5

Mean value 25.2 26.4 25.9 40.5 26.5 34.3 33.9 34.1 10.0 15.7 14.2 65.8 63.5 50.0 51.9

Standard

deviation

0.19 0.40 0.45 0.38 0.27 0.82 0.77 0.41 0.56 0.95 1.23 0.40 0.54 1.43 1.88

6 24.6 26.9 26.2 41.2 25.2 34.8 34.0 35.1 9.4 15.5 16.8 64.9 65.3 49.6 49.2

7 24.6 26 26.6 41.2 25.6 34.1 34.8 35.1 9.5 15.1 15.9 64.9 64.8 50.8 49.3

8 25.1 26.8 26.9 40.8 26.3 34.8 35.8 34.2 8.7 15.2 15.56

7

65.8 65.0 50.0 48.63

7

Mean value 24.8 26.6 26.6 41.1 25.7 34.6 34.8 34.8 9.2 15.3 16.1 65.2 65.1 50.1 49.0

Standard

deviation

0.29 0.49 0.35 0.23 0.55 0.40 0.92 0.51 0.43 0.20 0.65 0.52 0.26 0.57 0.36

ALL

SAMPLES

Mean value 25.1 26.5 26.2 40.7 26.2 34.4 34.3 34.4 9.7 15.5 14.9 65.6 64.1 50.1 50.8

Standard

deviation

0.32 0.41 0.51 0.42 0.53 0.67 0.89 0.53 0.64 0.75 1.41 0.53 0.92 1.12 2.06
10

Table 6: Fresh concrete analyses. Mixtures # 8-11.

The unshaded rows give the results of the concrete used for the CEMAGREF-IMG rheometer, while the shaded areas are for

the other rheometers.

% of paste by mass

fraction

% of 0.08/2 fraction % of 2/10 fraction % of 10/D fraction

Nominal values 29.3 28.8 40.8 26.9

Mixtures # 8 # 9 # 10 #11 # 8 # 9 # 10 #11 # 8 # 9 # 10 #11 # 8 # 9 # 10 #11

1 29.1 26.5 36.8 26.0 34.8 33.8 21.0 36.1 27.8 30.8 28.3 27.5 37.4 35.4 50.7 36.4

2 28.7 26.5 37.6 26.1 34.1 32.9 21.6 36.3 26.1 29.2 28.9 27.0 39.8 38.0 49.5 36.8

3 28.5 27.6 37.6 26.3 33.3 35.3 21.9 37.8 25.9 34.8 25.2 26.6 40.7 29.9 52.9 35.7

4 28.6 26.2 38.9 26.8 33.6 32.1 23.2 35.2 25.6 30.2 26.8 27.0 40.8 37.7 50.1 37.8

5 28.6 26.7 39.6 26.1 33.7 33.9 21.4 36.5 27.7 32.2 23.6 26.7 38.6 33.9 55.0 36.8

Mean value 28.7 26.7 38.1 26.3 33.9 33.6 21.8 36.4 26.6 31.5 26.5 27.0 39.5 35.0 51.6 36.7

Standard

deviation

0.23 0.53 1.13 0.32 0.60 1.20 0.83 0.94 1.04 2.17 2.17 0.35 1.45 3.28 2.27 0.77

6 28.6 26.5 37.4 26.6 33.7 32.8 23.9 36.1 28.6 29.6 30.8 25.7 37.7 37.6 45.4 38.2

7 29.8 26.6 38.6 25.6 35.9 33.6 22.9 35.5 29.3 28.8 28.9 27.3 34.8 37.6 48.2 37.2

8 29.7 28.4 26.5 35.6 35.8 36.3 27.5 33.3 27.1 36.9 30.9 36.6

Mean value 29.4 27.2 38.0 26.2 35.1 34.1 23.4 36.0 28.5 30.6 29.8 26.7 36.5 35.3 46.8 37.3

Standard

deviation

0.67 1.07 0.85 0.55 1.19 1.57 0.68 0.43 0.91 2.40 1.31 0.84 1.53 3.87 1.98 0.81

ALL SAMPLES

Mean value 29.0 26.9 38.1 26.3 34.3 33.8 22.3 36.2 27.3 31.1 27.5 26.9 38.3 35.1 50.2 36.9

Standard

deviation

0.53 0.74 0.98 0.38 0.99 1.27 1.06 0.77 1.33 2.13 2.46 0.54 2.08 3.24 3.12 0.79
11

3. Concrete Rheometers

3.1. The BML Rheometer

3.1.1. Description of apparatus

The ConTec BML viscometer 3, used in this test, is a coaxial cylinder rheometer for coarse

particle suspensions such as cement paste, grout, mortars, cement-based repair materials, and

concrete. It is based on the Couette rheometer [16] principle where the inner cylinder

measures torque as the outer cylinder rotates at variable angular velocity. It was developed in

Norway in 1987 [8, 9] after six years intensive work with the Tattersall Two-Point test

instrument. Since then, about 30 ConTec instruments have been made (as of Feb. 2001).

Several versions have been designed from the basic instrument. Figure 2 shows viscometer 3,

which is the best known, and viscometer 4, which is a smaller model, designed mainly for

mortar and very fluid concrete.

To perform the tests described in this report the ConTec BML viscometer 3 was used. To

simplify the wording, this instrument will be referred as BML or BML rheometer in the rest

of this report.

Figure 2: The ConTec viscometers: a) Version 3; b) Version 4.

The instrument is user-friendly, fully-automated, and is controlled by computer software

called FreshWin. Each test takes about 3 min to 5 min, from filling the bowl/material

container to emptying it. During testing, the material is exposed to shear for about one

minute (depending on the set-up used). A trolley is used for transporting the container (the

outer cylinder) full of concrete to ease the transport operation.

Several measuring systems can be used depending on the maximum aggregate size in the

suspension to be tested. Details are given in Table 7. Each measuring system is related to the

diameter of the inner cylinder. As an example, the most commonly used is the C-200, where

the C stands for Concrete and 200 represents the diameter of the inner cylinder in

millimeters. The C-200 measuring system was used for the tests reported here.
12

Table 7: Dimensions of the inner and outer cylinders of the five standard measuring

systems. The configuration used in the tests presented here is highlighted in gray

Measuring Inner radius Outer radius Effective height

Volume of testing

system (mm) (mm) (mm) Material

 M-130 65 78 100 ~1 liter

 M-170 85 100 120 ~3 liters

 C-200 100 145 150 ~17 liters

 C-200/1.3 100 131 150 ~15 liters

 C-240 120 Xx 150 ~25 liters

The parameters for each measuring system are incorporated as a standard set-up in the

FreshWin software. As shown in Figure 3 (to the left), a simple click and point allows

changes to the relevant parameters. The figure to the right shows the basic output of a test

result, namely a plot of torque vs. rotational frequency (velocity), displayed in real time

during testing. Figure 4 shows the inner and outer cylinder. Both cylinders contain ribs

parallel to their axis. Therefore, it is the material tested that will form the actual inner and

outer cylinder. This leads to a larger cohesion (or stickiness) between the cylinders and the

test material, hence reducing the danger of slippage.

 A B

Figure 3: Output from the FreshWin software: A) The menu-driven window used to

change relevant parameters; B) The basic output of a test result.

Figure 4: The inner and outer cylinder of the BML Viscometer 3 (or BML rheometer

hereafter).
13

The inner cylinder consists of three parts; the upper measuring unit, the lower unit and the

top ring (Figure 4 and Figure 5). It is only the upper unit that measures torque. The lower unit

is present to eliminate, or at least minimize, the so-called bottom effects. This insures that

only two-dimensional shearing of the testing material generates the torque, which the

instrument records.

At the bottom of any coaxial cylinder viscometer there is a complex three-dimensional

shearing in the material. In this bottom zone, the shear rate is not uniform for any given

angular velocity. Also, in some locations of this zone, the material may not have reached

equilibrium shear stress for the given angular velocity, even though it has reached

equilibrium in the upper zone where two-dimensional shearing exists. The functionality of

the pre-mentioned lower unit is to reduce this bottom effect.

The functionality of the top ring is somewhat less important, since its main objective is to

keep a constant height h where torque is measured. This is done to simplify the calculations

of the plastic viscosity and the yield value. If omitted, then the height has to be measured for

each test and put manually in the FreshWin software.

1

2

3

1: Inner cylinder, upper unit

2: Inner cylinder, lower unit

3: Top ring

a b c d

. 

Figure 5: The assembly of inner cylinder of the BML viscometer 3. This figure shows

the sequence for installing the inner cylinder.

Depending on mixture design, during initial shearing, a permanent volume increase in the

material can be observed. This positive dilatancy occurs between the inner and outer cylinder

(i.e. in the shearing zone). Generally, some amount of liquid, i.e., cement paste, fine

aggregate, etc., would be extracted from the test material near the outer cylinder and move in

the area of highest dilatancy, namely near the inner cylinder. As a consequence, a higher

aggregate content would appear near the outer cylinder, which will result in a plug flow. This

overall process is minimized in the BML, because the material within the inner cylinder can

provide the liquid. The same mechanism applies to the material between the ribs of the outer

cylinder.
14

3.1.2. Test procedures

Concrete and other cement-based materials, such as cement paste or mortar, are usually

considered to be a Bingham fluid, at least as a first approximation. In this case the viscosity

is given by:

•

= +

g

t

h m

0

( 1 )

where

h Viscosity of the Bingham fluid [Pa·s]

m Plastic Viscosity [Pa·s]

τ0 Yield value [Pa]

g& Rate of shear [1/s]

The equation for the shear stress is given by t = hg& , where t is the applied shear stress.

With the above viscosity equation, then the well-known shear stress equation for the

Bingham fluid is created:

0 0

t =hg& = (m+t g&)g& = mg& + t ( 2 )

Since the fluid material in a coaxial cylinder rheometer is dominated by shear flow, the

following constitutive equation or rheological equation of state is used [17]:

•

s = − pI + 2he ( 3 )

e& The strain rate tensor [1/s]

v

v Velocity [m/s]

σ Stress tensor [Pa]

p Pressure [Pa]

 I The unit dyadic (or the unit matrix)

In rheology, an equation of this type is the most fundamental tool for describing the

mechanical behavior of a fluid material. Its divergence describes the net force acting on a

continuum particle from its surroundings.

A top view of coaxial cylinder rheometer is shown in Figure 6. The outer cylinder (radius 

o

r )

rotates at angular velocity Ω (wo in the figure), while the inner cylinder (radius ir ) is

stationary and registers the applied torque T from the rheological continuum (i.e. from the

cement-based material).
15

Figure 6: A top view of a coaxial cylinder rheometer. The outer cylinder (radius 

o

r )

rotates at angular velocitywo, while the inner cylinder (radius ir ) is stationary and

registers the torque transferred through the fluid material.

As can be seen from Figure 6, it is very convenient to work in cylindrical coordinates, as is

done here. Using the general velocity field in Equation 3, it is only possible to achieve a

solution by numerical means:

r r z z

v v r z t i v r z t i v r z t i

v v v v

( ,q , , ) ( ,q, , ) ( ,q, , )

q q

= + + ( 4 )

But fortunately some reasonable assumptions about the flow can be made, which makes an

analytical approach possible:

1. At a low Reynolds number (i.e. with low speed and high viscosity η) the flow is stable

and it is possible to assume flow symmetry around the z -axis:

q q

v v r q z t i v r q z t i

r r

v v v

= ( , , , ) + ( , , , ) ( 5 )

2. If the bottom effect1 in the rheometer is eliminated by some geometrical means, height

independence can be assumed in the velocity function:

q q q q v v r t i v r t i

r r

v v v

= ( , , ) + ( , , ) ( 6 )

 

1

 The “bottom effect” means the effect from the shear stress generated at the bottom plate of the container. This

stress generates height dependence (i.e. z-dependence) in the velocity function.
16

3. Due to the circular geometry of the coaxial cylinder rheometer (see Figure 6), it is

reasonable to assume pure circular flow with q-independence:

q q

v v r t i

v v

= ( , ) ( 7 )

Since the rheological continuum a coaxial cylinder rheometer is driven by shear stress from

its outer cylinder and not by pressure distribution in the q-direction, it is also reasonable to

assume q-independence in the pressure function:

p = p(r,z,t) ( 8 )

The governing equation comes from Newton’s Second Law, more accurately called Cauchy’s

equation of motion [18]:

b

dt

dv v v

v

r = ∇ ⋅s + r ( 9 )

Solving the above equation with the given assumptions and with the boundary conditions of

νθ(ri)=0 and νθ(r0)= r0·Ω, produces:

















−

















= −

i

o

i

r

r r

h r r

T r

v r ln

1 1

4

( )

2 2 m

t

pm

q

( 10 )

( 11 )

In the above deviations, no assumption is made regarding the ratio of the cylinders, r0/ri.

Therefore, any ratio can be used in the above two equations.

Solving Equation 11 for Ω gives the well-known Reiner-Rivlin equation. The variable T is

the torque applied to the inner cylinder by the testing material. The relation between the

rotational frequency (N) and the angular velocity (Ω) of the outer cylinder is:

Ω = 2p ⋅N ( 12 )

In the M-170 measuring system, the ratio between the inner and the outer radii, r0/rI, is 1.18,

which ensures that only small variations [19] exist in shear rate across the gap between the

cylinders. For the standard C-200 system, which was used in the current test program, the

ratio of the radii of the outer and inner cylinders is 1.45. With this ratio, the rate of shear will

not be fully constant in the shearing zone at a given angular velocity of the outer cylinder.

This, however, does not prevent the calculation of the Bingham parameters of yield stress

and plastic viscosity, when the Reiner-Rivlin equation is used.
17

The software that controls the rheometer also calculates the speed, Np, below which plug

flow will occur [16] using Equation 13. If a data point is below the plug speed, it is removed

manually, by a simple click of the mouse. The underlying physics for a coaxial cylinder

rheometer and the derivation of Equation 13 has also been discussed by Tattersall and Banfill

[16]:

N

r r

r

P

o o

i

= ⋅ −











 −























 ⋅

τ

μ π

0

2

1

2

1

1

r

i 2

2

ln ( 13 )

The likelihood for plug flow occurring between the inner and outer cylinder during testing is

proportional to the ratio of τo/μ. If a plug occurs, then the error can be higher if the ratio of

the outer to the inner cylinder radii (ro/ri) is as big or bigger than the square root of the ratio

of G and To (see Figure 7) is:

G

T

r

r

o

0 i

2

=











 ( 14 )

The term To is the torque value measured at the lowest rotational frequency possible. Its

deviation from the term G occurs because of a plug inside the test material.

T

 

H

G 

 1

To

 Np N

T = G + HN

T: Torque (Nm) ; T O: Initial Torque

N: Rotation speed (rounds/s)

G : Flow resistance (Nm)

H: Relative viscos ity (Nms)

τ

μ

το 

1

 γ

τ = το + γμ

τ

: Shear stress (Pa)

γ: Rate of shear (1/s)

το

: Yield value (Pa)

μ: Plastic viscosity (Pas)

ð

Figure 7: The relation between torque measured by the rheometer and shear stress

3.1.3. Calibration

The calibration of torque and angular velocity is performed by an external load cell and a

stopwatch (or optical tachometer). The measured values are inserted into the FreshWin

software, which calculates the calibration constants. To confirm that the calibration is

correct, commercial products with known or stable rheological properties, like the oil,

CylEsso 1000, can be tested. Figure 8 shows the theoretical line and the kinematic viscosity

measured with the ConTec BML viscometer 3. Also shown are values measured with a tube

rheometer by the oil-testing laboratory Fjölver. Agreement is sufficiently accurate for
18

measurement of the viscosity of such a relatively low viscosity newtonian liquid such as the

CylEsso 1000 oil.

Figure 8: Output from the software during calibration of the BML rheometer
19

3.2. The BTRHEOM Rheometer

3.2.1. Description of the apparatus

The BTRHEOM is a parallel plate rheometer for soft-to-fluid concrete (slump higher than

100 mm, up to self-compacting concrete) with a maximum size of aggregate up to 25 mm.

The rheometer is designed so that a 7 L specimen of concrete having the shape of a hollow

cylinder is sheared between a fixed base and a top section that is rotated around the vertical

axis (see Figure 9). A motor located under the container rotates the upper blade system (see

Figure 10). The torque resulting from the resistance of the concrete to be sheared is measured

through the upper blades.

Z

Ω

Y

X

h

R1

θ r

R2

Ω R 2

Figure 9: Principle of the BTRHEOM rheometer

The dimensions of the sample are: R1 = 20 mm, R2 = 120 mm, and h = 100 mm (Figure 9).

The control of the rheometer (rotation speed, vibration), the measurements (torque and

rotation speed) and the calculation of the rheological parameters from the raw data are all

carried out by a special program (ADRHEO). The rotation speed can be varied between 0.63

rad/s (0.1 rev/s) and 6.3 rad/s (1 rev/s), though it is usually chosen between 0.63 rad/s (0.1

rev/s) and 5.02 rad/s (0.8 rev/s). The maximum torque that can be measured is about 14 N⋅m.

3.2.2. Test procedure

A seal is used to ensure that no concrete flows between the bucket and the rotating upper

cylinder and blocks the apparatus. The mean friction due to the seal is first evaluated in the

presence of water. From this value, the friction of the seal in the presence of concrete is

calculated and subsequently subtracted from the torque measurements to obtain the part of

the torque due to the concrete alone [11,1]. Once the bucket is filled, the concrete is vibrated

for 15 s to ensure good compaction of the concrete in the bucket (except for self-compacting
20

concrete). This pre-vibration is optional. The frequency of pre-vibration can be selected in

the range from 36 Hz to 55 Hz. After the pre-vibration, the measurement itself starts. The

rheometer is controlled by the rotation speed.

The basic test consists of one or two consecutive series of five to ten measurement points,

made at increasing or decreasing rotation speed. For example, if the test consists of two

series, both may contain the same number of points, and have the same upper and lower

limits, but each series can be made at either increasing or decreasing rotation speed, and with

or without vibration. After completion of the test, the concrete can be vibrated again if

required. For each data point, a torque measurement (Γ) is taken after a time interval of about

20 s during which the rotation speed N is constant. This delay allows for stabilization of the

torque.

3.2.3. Analysis of the data

The recording of the various (Γ, N) data pairs is carried out by the computer. The relationship

between torque and rotation speed is a function of the form:

b Γ = Γ0 + A N ( 15 )

From this relationship and the strain field shown in Figure 9, the rheological behavior of the

concrete can be deduced. It is assumed that the concrete has a Herschel-Bulkley behavior that

means that the shear stress τ is related to the shear velocity gradient by the following

equation:

b

t =t + ag&

0

 ( 16 )

For practical purposes, b is fixed between 1 and 3 (see [33]). Finally, the flow behavior of the

concrete is approximated by the Bingham law with only two rheological parameters:

τ = τ + μγ&

0

( 17 )

where τ0 is the shear yield stress calculated with Equation 17 and μ the plastic viscosity

deduced from a and b in Equations 18 and 19 [20]. The details of the derivation of the

equations relating τ0 and μ to Γ0, A and b in Equation 15 are given in Reference [20]. These

equations are:

3 0

1

3

2

0

2 (R R )

3

Γ

π −

τ = ( 18 )

A

(R R )

h

(2 )

(b 3)

a 0.9 b 3

1

b 3

2

b

b+1 + +

π −

+

= ( 19 )
21

b 1

max b 2

3a −

γ

+

μ = & ( 20 )

where 

h

maxR2

max

Ω

γ& = is the maximum strain rate used in the measurement.

Alternatively, the Bingham parameters may be directly calculated from Equation 15

assuming b = 1. However, the result (in terms of τ0 and μ values) is different from the value

calculated using Equations 17 to 19 [20].

Figure 10: The BTRHEOM rheometer showing the blades at the top and bottom of the

bucket containing the concrete.
22

3.3. The CEMAGREF-IMG Rheometer

3.3.1. Description of the apparatus

The CEMAGREF-IMG rheometer is a large coaxial-cylinder rheometer that contains

approximately 500 L of concrete (see Figure 11 and Figure 12). The outer cylinder wall is

equipped with vertical blades, and the inner one with a metallic grid in order to limit the

slippage of concrete (see Figure 13). A rubber seal is fitted to the base of the inner cylinder to

avoid any materials leakage between the cylinder and the container bottom.

This apparatus was originally developed to study mud flow rheology [21]. The primary

advantage of this instrument is the large dimensions with respect to the maximum aggregate

size. However, the geometry is not a pure Couette one, because the ratio of the inner radius to

the outer radius is too large, 1.57. Therefore, some plug flow is to be expected when testing

viscoplastic materials that have a yield stress. It means that for most tests, only the inner part

of the concrete sample will be sheared, at least for the lower values of rotation speed (see

Figure 13).

Inner cylinder

Outer cylinder

Motor axis

Concrete sample

Rubber seal

Load cells

Ø 120 cm

Ø 76 cm

9

0

c

m

Figure 11: Schematic of the CEMAGREF-IMG rheometer
23

Figure 12: Picture of the CEMAGREF-IMG rheometer

Figure 13: Top view of the CEMAGREF-IMG rheometer with grid on the inner

cylinder and blades on the outer one .

Grid

Blade
24

The rotation movement is transmitted from the motor axis to the inner cylinder through two

mechanical linkages, both of which include a load cell (see Figure 14). The load cells, which

were calibrated by LCPC prior the tests reported here (see calibration report in Appendix D),

measure the total torque transmitted to the concrete.

Figure 14: Sketch showing set-up of the calibrated load cells to measure the torque

The rotation velocity is measured by a dynamo, the axis of which is connected by a wheel to

the cap of the rotating inner cylinder (see Figure 15). This speed-meter was also calibrated by

LCPC prior to the tests reported here (see calibration report in Appendix D).

Thus, during a test, three voltages are recorded at a frequency of 5 Hz with a PCMCIA

acquisition card IOTEK DAQCARD 112B (see verification report in Appendix D):

• two for the load cells;

• one for the speed-meter.

Data are saved in text files with the following format:

• first column (CH00): the torque value C1 (in N⋅m) given by the load cell n°1;

• second column (CH01): the torque value C2 (in N⋅m) given by the load cell n°2;

• third column (CH02): the rotation speed Ω (in rad/s) of the inner cylinder;

The total torque C is given by the equation C=C1+C2

The following relationships were used for conversion of the voltages measured (V1,V2,V3 in

volts).

• for the load cell n°1: C1 = 998.84*V1

• for the load cell n°2: C2 = 1000.2*V2

• for the speed-meter: Ω = -0.6225*V3+0.0322

The calibration curves are shown in Appendix D.
25

Rotating inner

cylinder

Ø695 mm

Wheel

Ø48.5 mm

Dynamo

Fixed outer

cylinder

Datalogger

Figure 15: Description of the speed-meter

3.3.2. Test procedure

Tests are carried out by manual control of the engine power. The procedure is as follows:

• The torque needed to counteract the seal friction is measured in presence of a small

amount of concrete in the rheometer (approximately 55 mm of concrete is needed to cover

the seal) for different decreasing rotation speeds.

• The rheometer is then filled with concrete and the height of the concrete is measured.

• The rotation speed is rapidly increased up to a maximum and then decreased in 6 to 8

steps lasting around 10 s each, down to a minimum. Torque and rotation speed are

recorded at a frequency of 5 Hz.

• During the test, the width of the sheared zone is manually evaluated with a ruler on the top

surface of the concrete for different rotation speeds.

3.3.3. Analysis of the data

Notation

Rint = 0.38 m: inner cylinder radius

Rext = 0.60 m: outer cylinder radius

h (in m): height of concrete test sample (total height of concrete minus 0.055 m,

corresponding to the concrete used for the seal calibration)

C (in N⋅m): torque applied to the concrete sample

Ω (in rad/s): rotation speed of the inner cylinder

r (in m): radial coordinate of a unit concrete cylinder

ω (in rad/s): rotation speed of a unit concrete cylinder

γ& (in s-1): strain rate

τ (in Pa): shear stress
26

τ 0 (in Pa): shear yield stress in Bingham model

μ (in Pa s): plastic viscosity in Bingham model

Rc (in m): critical radius beyond which the concrete is not sheared (dead zone)

Ec: width of the sheared zone (Ec=Rc-Rint)

Direct calculation of the shear yield stress

During a test, the width Ec of the sheared zone beyond which there is a “dead zone” (see

Figure 16) was measured for different rotation speeds. For the sheared part of the concrete

sample, the equilibrium equation gives a theoretical value of τ0 which depends on Ec and C:

( )

2

int c

0

2 h R E

C

π +

τ = ( 21 )

r

Sheared zone

Dead zone

w

t

t o

Inner cylinder

r

Ec

Figure 16: Diagram of plug flow phenomenon

For each rotation speed, the corresponding torque C was calculated according to the best fit

curve (see Section 3.3.3). Then it was possible to calculate a set of theoretical values of the

shear yield stress τ0 for the given set of C values (i.e. the set of rotation speeds).

This analysis is particularly interesting because it does not need any assumption about the

strain rate field between the concrete sample and the inner cylinder. On the contrary, to

calculate both τ0 and μ, it is necessary to assume that there is no slippage, which means that

Ω is the rotation speed of the concrete near the surface of the inner cylinder. In this case, it is

possible to analyze the best-fit torque-rotation speed curves according to Bingham models

accounting for the plug flow phenomenon. This equation is known as the Reiner-Rivlin
27

equation. As the Bingham model gave a good fit to the experimental results, the HerschelBulkley model was not used in the analysis.

Analysis with Bingham model

Fresh concrete can be considered to be a Bingham fluid with the following equations:

τ = τ + μγ&

0 ( 22 )

τ

π

=

C

2 hr

2 ( 23 )

r

r

∂

∂ω

γ& = − ( 24 )

The critical radius Rc beyond which the concrete is not sheared (dead zone) is given by:

































π τ

=

0

c int ext 2 h

C

R max R ;min R ; ( 25 )

If we make the assumption that there is no slippage between the inner cylinder and concrete,

we have:

dr

r

c

int

R

R

∫

∂

∂ω

Ω = − ( 26 )

c

0 int

2

c

2

int

R

R

2 0

R

R

ln

R

1

R

1

4 h

C

dr

r

1

2 hr

1 C

c

int

μ

τ

+

















−

π μ

= 













− τ

μ π

Ω = ∫ ( 27 )

Then for 0

2

int C ≥ 2πhR τ :

[ ( ) ] ln C

4 h R 2

C

ln 2 h R 1

2

F(C)

0

2

int

2

0 int

0

μ

τ

−

π μ

π τ − +

μ

τ

Ω = = ( 28 )

or else Ω=0.
28

Fitting of the torque versus rotation speed curves

The curve of torque versus rotation speed data obtained for the seal is fitted with the

following empirical function:

Cseal(Ω) = C0,seal + aΩ ( 29 )

In the second step, the test performed with the rheometer full of concrete gives a set of points

(Ωi, Call,i) where Call,i is the total torque applied to the cylinder. The net torque Ci actually

applied on the concrete sample is obtained with the following equation:

( ) i all,i 0,seal i C = C − C + a Ω ( 30 )

The set of experimental points (Ωi, Ci) obtained is then fitted with the curve Ω = F(C) (see

equation 25) as follows:

• for a given τ 0 , μ and for each Ωi, we calculate ( )i

1 Cth,i = F Ω−

. Unfortunately, the

function F has the following form F(x) = Ω0 + a x + bln x , so F

-1 can not be

analytically written. A function was therefore created under MSExcel that calculates

each Cth,i by solving F(C ) 0 th,i − Ωi = with the Newton method.

• τ 0 and μ are adjusted with the MSExcel solver, in order to minimize the mean

quadratic error:

( )

n

C C

n

2

∑ − th,i

ε = ( 31 )

For the two curve-fittings, only the points from the decreasing part of the curve and for

rotation speeds higher than 0.1 rad/s are used (see Figure 17 and Figure 18). The lower limit

of 0.1 rad/s is chosen because the speed-meter was calibrated only for speeds higher than this

value and because below this value, the inner cylinder rotates by jerks, which generates

dynamic effects that disturb the torque measurements.
29

0

100

200

300

400

500

600

700

800

0 20 40 60 80 100 120 140

Time (s)

Torque (Nm)

0,00

0,50

1,00

1,50

2,00

2,50

Rotation speed (rad/s)

Torque

Speed

Only the part of

the curves

between these

two limits is

analyzed

Torque

Speed

Figure 17: Typical curves versus time obtained during a test.

0

100

200

300

400

500

600

700

800

0,00 0,50 1,00 1,50 2,00 2,50

Rotation speed (rad/s)

Torque (Nm)

Only the part of

the curve

between these

two points is

analyzed

Figure 18: Torque-rotation speed curve for the same test as in Figure 17.
30

3.4. The IBB rheometer

3.4.1. Description of the apparatus

This apparatus is an instrumented and automated version of the existing apparatus (MKIII)

developed by Tattersall [16]. It was modified in Canada by Beaupré [12] to study the

behaviour of high-performance, wet-process shotcrete. The apparatus is fully automated and

uses a data acquisition system to drive an impeller rotating in fresh concrete. The test

parameters are easy to modify in order to produce any required test sequence. The analysis of

the results is also automated and the rheological parameters, yield stress (in N⋅m) and plastic

viscosity (in N⋅m⋅s), are displayed on the screen. The user may also retrieve an individual

data set to plot the flow curves manually.

This apparatus can be used to test concrete with slumps ranging from 20 mm to 300 mm. It

has been successfully used for self-compacting concrete, high-performance concrete, pumped

concrete, dry and wet-process shotcrete, fiber reinforced concrete, and normal concrete. It

has also been used on a few job sites as a means of quality control.

The general view of the apparatus is shown in Figure 19, while Figure 20 shows the detail of

the bowl and impeller used for concrete and mortar respectively. The impeller shape and the

planetary motion are as developed for the Tattersall MKIII (LM) apparatus. The concrete

bowl leaves a 50 mm gap between the impeller and the bowl while the mortar bowl gives a

25 mm gap. The recommended maximum size aggregate is 25 mm for the concrete bowl and

12 mm for the mortar bowl. The sample size is 21 L for the concrete bowl and 7 L for the

mortar bowl.

Figure 19: The IBB Rheometer
31

Bowl = 360 mm diameter

 250 height

130

100

Concrete level = 200 mm

Gears for planetary motion

 16DP and 45 DP

Bowl = 230 mm diameter

 180 height

85

100

Mortar level = 150 mm

Gears for planetary motion

 16DP and 45 DP

(a) (b)

Figure 20: Details of the H-shaped impellers, bowls and planetary motion for IBB

rheometer for concrete (a) and mortar (b) . Dimension in mm

3.4.2. Analysis of the data

The computer software, developed for use with the rheometer, calculates the following

parameters from the torque/speed data: H, G, M, B and R2. Figure 21 indicates the meanings

of these parameters. H and G could be related to plastic viscosity and yield stress

respectively. R2 is used to determine the significance of the calculations. A R2 of 1 indicates

that the data points lie on a straight line, while a value lower than 0.90 indicates that the data

points are not on a straight line. The first point and the points for which the speed is 0 are not

used in the calculations.
32

IBB rheometer calculation example

0

0.2

0.4

0.6

0.8

1

0 5 10 15 20 25

Torque (N.m)

Speed (rev/s)

H

1

y = M x + B

y = 0.11 x - 0.68

R2 = 0.98

M=1/H

G = -B/M

Figure 21: Example of calculation with indication of the meaning of the parameters. Y=

speed; x = Torque
33

3.5. The Two-Point Rheometer

3.5.1. Description of the apparatus

The Two-Point workability test used in the program is an updated version of the apparatus

first described by Tattersall and Bloomer [22]. The principles remain the same, with the

option of two impeller systems - an axial impeller with four angled blades set in a helical

pattern around a central shaft which imparts a stirring and mixing action to the concrete (the

MH system), and an offset H-impeller with a planetary motion through the concrete (the LM

system). The former, which is suitable for slumps in excess of about 100 mm, was used in the

current program. Dimensions of the impeller and bowl are given in Figure 22.

The impeller is driven by a variable speed hydraulic drive unit motor through a gearbox; the

overall arrangement is shown in Figure 23. Torque is measured indirectly through the oil

pressure in the drive unit. The linear relationship between the oil pressure and torque was

obtained by prior calibration with a plummer block, radius arm and spring balance system

fully described elsewhere [16]. During testing, the oil pressure can be observed on a pressure

gauge, or captured digitally on a computer via a pressure transducer fitted to a tapping in the

drive unit casing. The impeller speed is similarly captured from a tachometer fitted to the

drive shaft. The speed is controlled manually.

Figure 22: Impeller and bowl dimensions (in mm)
34

Figure 23: The overall arrangement of the Two-Point test apparatus

3.5.2. Test procedure

Previous studies [23] had shown that a suitable testing procedure was to obtain the

torque/impeller speed relationship in a single downward sweep of the speed from 6.2 rad/s to

0.62 rad/s (1 rev/s to 0.1 rev/s) in about 30 s. A guide trace on the computer screen was used

to ensure consistency between tests. The voltages corresponding to speed and pressure were

recorded four times per second, giving approximately 120 data points per test. As well as

testing with the impeller rotating in the concrete, it is necessary to record the oil pressure

with the impeller rotating in air (called the idling test) over a similar speed range. The net

pressure between the idling and concrete test then gives the torque needed to rotate the

impeller in the concrete.

This relationship between torque and speed is of the familiar Bingham form:

T = g + hN ( 32 )

where g is the yield value term and h the plastic viscosity term.

Prior calibration was also carried out to determine the relationship between these two terms

and the Bingham parameters of yield stress (τ0) and plastic viscosity (μ) in fundamental

units. The calibration theory is described in full in Chapter 7 of Tattersall and Banfill [16].

The principles can be summarized as follows.

It is assumed that in the apparatus there is an average effective shear rate given by

= KN

•

g ( 33 )
35

where N is the impeller speed about its own axis and K is a constant. Knowing the value of K

and another constant G permits g and h to be expressed in terms of τ0 and μ using

t0 = K /Gg ( 34 )

m = 1/Gh ( 35 )

The value of G is determined by observing the linear relationship between T and N in the

apparatus for a Newtonian liquid of known viscosity η. G is the constant of proportionality

in:

T / N = Gh ( 36 )

The value of K is determined by comparing the power law relationship between T and N of

the form

q

T = pN ( 37 )

obtained in the two point apparatus for a power law fluid with the flow curve determined

separately in a rheometer as

a

t = rg ( 38 )

(p, q, r and s are constants)

Provided that the range of shear rates are similar in the Two-Point apparatus and in the

rheometer then

1/( 1)

( / )

−

=

s K p rG ( 39 )

The indices for the power law fluid, q and s, should be equal and Equation 33 assumes this. If

they are not equal, it should be written as [23]

( −1) /( −1)

•

=

q s

g KN ( 40 )

The Newtonian fluid used was a silicone with a viscosity of about 28 Pa⋅s at 22 oC. The value

of G was determined at three temperatures, 22 oC, 27 oC and 32 oC, with the average value

being 0.0587 m3.

The power law fluid was an aqueous solution of carboxymethyl cellulose, at two

concentrations, 2.5 % and 3 % by mass fraction. The average value of K was 7.1.

The test procedure was as follows:

• The machine was run with the impeller rotating for at least 0.5 h before testing to

allow the oil in the drive unit to reach equilibrium temperature.

• An idling test was carried out
36

• The concrete was loaded into the bowl with the impeller rotating at about 1.2 rad/s

(0.2 rps) until the impeller blades were completely immersed in concrete

• The speed was increased to 6.2 rad/s (1 rev/s), and the data recording was then started

and continued whilst reducing the speed to zero over about 30 s.

• The impeller was disconnected and the idling test repeated.

3.5.3. Analysis of the data

The data in the form of voltages proportional to speed and torque was recorded directly into

an Excel spreadsheet. After discarding the tail of data at either end of the test, the following

procedure was used for the concrete test data to eliminate the falsely high pressure kicks that

can arise from aggregate particles trapping and interlocking:

• A best fit relationship between pressure and speed was obtained by linear regression

• The standard deviation of the residuals between the measured and predicted values

was calculated

• Data points more than twice this standard deviation from the predicted value are

substituted by the predicted value and a second ‘corrected’ regression line obtained.

In practice, this increases the correlation coefficient of the regression line, but does not

significantly alter the slope and intercept.

The slope and intercept were also obtained for each of the two idling tests and averaged. The

two regression equations were then converted from voltages to oil pressure and impeller

speed and the net pressure/speed relationship (Equation 32) obtained by subtraction.

This gave the yield value and plastic viscosity terms g and h, which were converted into yield

stress and plastic viscosity in fundamental units using the values of G and K determined by

calibration and Equations 34 and 35 above.
37

4. Results

4.1. Quality control measurements: Slump, modified slump, density

The concrete quality was checked immediately after mixing with the measurement of the

slump according to the ASTM C143 standard. These results are reported in Table 8 as

“slump at mixer”. If the slump was not on target, water or HRWRA were added to the mixer

and the concrete remixed as described in Section 2.3. In some but not all cases, the concrete

slump was re-measured at the mixer. At the same time the tests were conducted, using the

various rheometers, a slump was measured using the standard method (ASTM C143) and a

modified method [24]. This latter method also gives the rate of slumping by measuring the

time for the concrete to slump by 100 mm. These times are reported along with the slump

measured in Table 8. The final slump is also recorded. The relationship between the slumps

measured by the two methods is shown in Figure 24. The correlation coefficient, R2, of 0.95

is considered satisfactory (see also the critical review of R2 in Section 5.1.2).

The density of the fresh concrete was also measured using a volumetric method. The results

are reported in Table 8. These results were used to calculate the exact concrete composition

as reported in Section 2.2.

R

2

 = 0.951

0

50

100

150

200

250

0 50 100 150 200 250

Slump standard [mm]

slump modified [mm]

Figure 24: Comparison of the slumps measured by the standard method and the

modified method. The dotted line represents the 45 ° line.
38

 Table 8: Slump Measurements

Slump Spread Modified Slump

Mixture #

Date/timeg

MM/DD/YY

at mixer

[mm]

in hall

[mm]

Std.

[mm]

Mod.

[mm]

Slump

[mm]

Time

[s]

Density

[kg/m3]

Comments

1 10/24/00 10:19 110 97 97 NA 2407

2 10/24/00 12:05 240 225 475 420 230 1.9 2361

3 10/24/00 14:53 160a187 184 2.22 2372

4 10/24/00 16:57 110 90 67 NA 2373

5 10/25/00 9:56 120b105 74 NA 2409

6 10/25/00 12:11 227 338e351 217 2 2427

7 10/25/00 15:14 232 467f391 210 NA 2399 Spread at 15:26 was 479 mm

7 repeat 398 237 1.26

8 10/25/00 18:03d160 128 130 1.6 2356

9 10/26/00 9:54d220c232 400 360 226 2.76 2318

10 10/26/00 11:40 225 222 216 NA 2344

10 repeat 225 1.45

11 10/26/00 15:10d185 132 117 2.17 2275

12 10/27/00 10:17 150c150 169 1.57 2349

Notes:

a) Water was added after this slump was measured

b) 2nd measurement at 10:10 was 11.2 cm; 3rd measurement at 10:26 was 10.8 cm

c) HRWRA added after this measurement

d) Time estimated from recorded pictures

e) Flow spread at mixer was 440 mm

f) Flow spread at mixer was 610 mm

g) all times use 24 h clock

NA = Non Available
39

4.2. Comparison between rheometers

For each rheometer, the yield stress and the plastic viscosity were calculated as described in

Section 3. Detailed data and graphs can be found for each rheometer in Appendix C. Table 9

shows the data obtained. It should be noted that one of the rheometers, IBB, does not provide

the results in fundamental units. Therefore, most graphs have double axes to ensure that the

IBB data are correctly represented.

Table 9: Yield stress and viscosities calculated from the measurements

BML BTRHEOM CEMAGREFIMG*IBB Two-Point

Yield

stress

Plastic

Viscosity

Yield

stress

Plastic

Viscosity

Yield

stress

Plastic

Viscosity

Yield

stress

Plastic

Viscosity

Yield

stress

Plastic

Viscosity

Mixture #

Pa Pa⋅s Pa Pa⋅s Pa Pa⋅s N⋅m N⋅m⋅s Pa Pa⋅s

1 738 114 1619 181 1832 10.84 14.72 919 61

2 76 17.4 406 18 437 3 0.34 5.34 80 13

3 408 82.4 771 136 3.67 13.20 314 83

4 840 72 2139 51 2138 7.44 11.65 1059

5 910 108 1753 94 3.91 14.61 698 19

6 139 45 505 78 487 63 1.80 10.31 145 41

7 90 32.7 549 54 410 43 0.86 9.31 98 38

8 717 29 1662 67 1417 5.71 8.84 689 22

9 125 15 624 25 504 3 0.95 6.06 159 19

10 248 35.9 740 50 535 43 1.98 8.88 253 19

11 442 29 1189 27 1034 21 3.97 6.57 516 16

12 584 39 1503 38 929 47 6.23 9.07 525 22

Note: * See Appendix C, Section 5.3.3 for the explanation for the empty cells

In this chapter we will present some comparisons between the data. A more detailed

discussion of the data is found in Section 5. The data will be shown in various ways to:

• Determine the relationship between the rheometer measurements and the slump or

modified slump measurements

• Examine the relative responses of the rheometers for each mixture.

• Establish the correlation functions and coefficients between any pair of rheometers

Figures and tables will be presented with comments to illustrate each of these points.

4.2.1. Comparison with the slump and modified slump test

As the use of these rheometers is not wide spread at this time, it was interesting to determine

the correlations between values obtained with the rheometers and the more commonly used

slump test. In this series of tests, two versions of the slump test were performed: the standard

slump test as described in ASTM C143 and the modified slump test developed by Ferraris

and de Larrard [24]. The slump is expected to be correlated with the yield stress, [24, 25]

while the modified slump test time and final slump value should be used to compare to the

plastic viscosity.
40

Figure 25 and Figure 26 show the results obtained. It seems that the yield stress (Figure 25) is

correlated with the slump for each rheometer, as expected. This point is further developed in

Section 5.3. On the other hand, the plastic viscosity measured by the rheometers (Figure 26)

is not correlated with the plastic viscosity calculated from the modified slump tests results.

This is probably due to the fact that the coefficients used to calculate the plastic viscosity

from the slumping time were fitted from a set of data points using only round aggregates.

Also, the coefficients were calculated from a set of data [26] with a range of plastic

viscosities from 20 Pa⋅s to 1000 Pa⋅s while here the range is from 20 Pa⋅s to 140 Pa⋅s.

Therefore, the modified slump test was not able to distinguish between concretes within this

narrower range of plastic viscosities. Other type of models could perhaps be applied to more

successfully correlate the plastic viscosity measured with the rheometers and the results from

the modified slump tests [27].

0

500

1000

1500

2000

2500

50 100 150 200 250

Slump [mm]

Yield stress [Pa]

0

2

4

6

8

10

12

Yield stress [N.m]

BML

BTRHEOM

Cemagref

2 point

IBB

Figure 25: Comparison of standard slump and yield stress as measured with the five

rheometers. The second axis in N×m gives the results obtained with the IBB.
41

0

20

40

60

80

100

120

140

160

180

200

0 100 200 300 400 500

Viscosity from mod slump [Pa.s]

Viscosity [Pa.s]

0

2

4

6

8

10

12

14

16

Viscosity [N.m.s]

BML

BTRHEOM

Cemagref

2 point

IBB

Figure 26: Comparison of plastic viscosity calculated from the modified slump test and

plastic viscosity as measured with the five rheometers. The second axis in N×m×s gives

the results obtained with the IBB.

4.2.2. Variation of the values by concrete composition

The concrete mixtures used were designed to cover a wide range of rheological performance

as stated in Section 2.2. It might be expected that all the rheometers would rank the yield

stresses in the same order, and similarly for the plastic viscosities. In other words, the values

should be high or low for the same mixtures. There are two ways to represent the rankings:

• Plot the measured value versus the mixture number.

• Rank all the concretes according to each rheometer and see if the rankings are the same,

using the Kendall’s coefficient of concordance W [see Appendix E]

4.2.2.1. Analysis of variation of the yield stress and plastic viscosity by mixture

At first glance, Figure 27 and Figure 28 seem to show that the yield stress values are

synchronized better between rheometers than are the plastic viscosity values. In Sections

4.2.3 to 4.2.5, it will be shown that a certain correlation between plastic viscosities measured

with the various rheometers does, however, exist.
42

0

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 10 11 12

Mixture #

Yield stress [Pa]

0

2

4

6

8

10

12

Yield stress [N.m]

BML

BTRHEOM

Cemagref

2 point

IBB

Figure 27: Comparison of the yield stresses as measured with the rheometers

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7 8 9 10 11 12

Mixture #

Viscosity [Pa.s]

0

2

4

6

8

10

12

14

16

Viscosity [N.m.s]

BML

BTRHEOM

Cemagref

2 point

IBB

Figure 28: Comparison of the plastic viscosities as measured with the rheometers
43

4.2.3. Relative rank of the data by each rheometer

The graphs of yield stress and plastic viscosity versus mixture number (Figure 27 and Figure

28) show there is some similarity between the results of the different rheometers (especially

for yield stress). The next step is to compare the classification of the concretes by apparatus:

will the mixtures be ranked in the same order by yield stress and plastic viscosity?

This type of comparison can be quantified by Kendall’s coefficient of concordance, W, [28]

(see Appendix E). First, the ranking needs to be established for each concrete by each

rheometer, both for yield stress (Table 10) and plastic viscosity (Table 11). This comparison

is made only on the rank given by each apparatus, which enables one to include also the

slump test (with yield stress) and the IBB (for both “equivalent” yield stress and plastic

viscosity). Nevertheless, the same number of data points should be available for each

rheometer. This precludes the CEMAGREF-IMG from the comparison2. When the

measurements obtained with two different mixtures are identical, the rank assigned to both of

them is the average between the two ranks. For instance, with the BML, mixtures #8 and #11,

both give a plastic viscosity value of 29 Pa⋅s. The rank would be 8 and 9 for these mixtures

for the plastic viscosity. The rank assigned will be 8.5 for both mixtures. The same procedure

is applied for the Two-Point tests for mixtures #8 and #12, and mixtures #5, #9 and #10.

From the tables, it is clear that there is some correlation between the various devices for both

yield stress and plastic viscosity. We have already seen (Figure 27) a strong correlation

between the yield stress ranking, but Table 11 shows a correlation also on the plastic

viscosity measurements. For instance, Mixtures #2, #3, #8 and #10 show similar rankings for

yield stress (Table 10). Mixtures #1, #10 and #11 show similar ranking for the plastic

viscosity (Table 11).

Calculations of the Kendall’s coefficient of concordance, W (Appendix E), show it to be

equal to 0.941 for the results in Table 10 and 0.910 for the results in Table 11. These values

of W need to be compared with a reference value taking into account the number of samples

(12 in this case) and the number of devices (5 for yield stress and 4 for plastic viscosity). The

reference values obtained from Ref. [28] are 0.336 for the yield stress and 0.415 for the

plastic viscosity. This is a test of the independence of the classifications, i.e., the

classifications are not independent (at the 95% confidence level) if the value of the W

parameter is greater than the reference value. The test shows that the classifications by the

various devices are not independent, and this implies that concretes would be classified in the

same order by whatever instrument was used.

 

2

 To also compare the results of Cemagref, another comparison should be made on the mixes for which it has

given a reliable result.
44

Table 10: Ranking of the yield stresses of the mixtures as determined by the rheometers

and the slump. The mixtures are ranked in decreasing order of yield stress from 1 to 12.

The higher the slump, the lower the yield stress.

Ranking

according

to

Mixture # 1 2 3 4 5 6 7 8 9 10 11 12

BML 3 12 7 2 1 9 11 4 10 8 6 5

BTRHEOM 4 12 7 1 2 11 10 3 9 8 6 5

IBB 1 12 7 2 6 9 11 4 10 8 5 3

Two-Point 2 12 7 1 3 10 11 4 9 8 6 5

slump 2 9 7 1 3 10 12 4 11 8 5 6

Table 11: Ranking of the plastic viscosity of the mixtures as determined by the

rheometers. The mixtures are ranked in decreasing order of plastic viscosities from 1 to

12.

Ranking

according

to

Mixture # 1 2 3 4 5 6 7 8 9 10 11 12

BML 1 11 3 4 2 5 8 8.5 12 7 8.5 6

BTRHEOM 1 12 2 7 3 4 6 5 11 8 10 9

IBB 1 12 3 4 2 5 6 9 11 8 10 7

Two-Point 2 11 1 12 8 3 4 5.5 8 8 10 5.5

4.2.4. Graphical comparison of pairs of rheometer results

A graphical comparison of the Bingham parameters, yield stress and plastic viscosity, for

each pair of rheometers should give a qualitative estimate of the correlation between the

results obtained by the various rheometers. If any pair of rheometers gave identical values,

the data points, plotted on a scatter graph with identical scales for both axes, should be on a

45 degree straight line, or a line of equality, passing through the origin. For each pair of

rheometers, plots were made for yield stress and for plastic viscosity. In each plot, the

equality line is shown together with linear regression (Section 4.2.5) and the 95% confidence

range. Due to the fact that no mixture was repeated, the 95% confidence range is calculated

based on a single value and a linear regression. Note that the line of equality was not plotted

for the IBB rheometer because the units are not the same as for the other rheometers. Figure

29 to Figure 38 at the end of this section show all these plots. The regression line parameters

are given in Section 4.2.5. As shown in Table 15 and Table 16, the correlation functions

coefficients are not the same on both sides of the symmetry, therefore, we show two graphs

for each pair of rheometers.

As discussed below, one of the plastic viscosities measured with the Two-Point test was

probably an outlier. This is discussed in Section 3.5.3 and in Appendix C. Therefore, a
45

second set of pair graphs in Figure 39 and Figure 40, omit the value for plastic viscosity from

Mixture #4 as measured by the Two-Point test.

These figures show, at a glance, how the results from different rheometers correlate with

each other.

4.2.5. Correlation functions and coefficients between pairs of rheometers

One objective of this project was to determine the degree of correlation between the

rheometers. Correlation relationships allow the user of any one rheometer to compare results

with those obtained with any of the other rheometers. Two methods were selected to show

the correlation between any two rheometers:

• Calculation of the correlation coefficient

• Fitting of a linear function to data from pair of rheometers.

These functions and correlation coefficients were calculated for yield stress and plastic

viscosity separately.

The correlation coefficient R measures the degree of association between two variables. For

two variables, x and y, R is calculated from [29]:

∑ ∑

∑

− −

− −

=

2 2

( ) ( )

( )( )

x x y y

x x y y

R

i i

i i

( 41 )

The correlation coefficient R measures the degree of linear association between variables. It

is possible for two variables to have a high degree of non-linear association and still have a

low correlation coefficient. The value of R range between –1 and 1. For negative values of R,

y decreases as x increases. For yield stress and plastic viscosity the correlation coefficients R

were calculated for each pair of rheometers. The calculated R values for each pair of results

are shown in Table 12 and Table 13. Discussion of the significance of these results is given

in Section 5.1.2.

During the testing and subsequent analysis, it was apparent that the properties of some of the

mixtures approached the limits of suitability for some rheometers. A case in point is mixture

# 4 when tested in the Two-Point test. This mixture had the lowest slump, and may not

therefore have been efficiently mixed by the impeller. A plastic viscosity of near-zero was

obtained, which should be treated with suspicion. There are, however, no rigorous reasons

for excluding it from the statistical analysis, even though this has added to the degree of

scatter. If this point is not considered in the calculation of the correlation coefficients for the

plastic viscosity, the results in Table 14 are obtained. In this case, the correlation coefficients

between the results from Two-Point tests and the other rheometers are higher.
46

Table 12: Correlation coefficients for yield stress

BML BTRHEOM CEMAGREFIMGIBB Two-Point Slump

BML 0.97 0.95 0.81 0.94 -0.96

BTRHEOM 0.94 0.82 0.97 -0.95

CEMAGREFIMG0.90 0.99 -0.95

IBB 0.90 -0.86

Two-Point -0.96

Slump

Table 13: Correlation coefficients for plastic viscosity

BML BTRHEOM CEMAGREFIMGIBB Two-Point Mod Slump

BML 0.84 0.98 0.96 0.45 -0.41

BTRHEOM 0.91 0.86 0.79 -0.29

CEMAGREFIMG0.98 0.75 -0.41

IBB 0.52 -0.40

Two-Point -0.15

Mod Slump

Table 14: Correlation coefficients for plastic viscosity if Mixture #4 for Two-Point test

is not considered (see text for rationale).

BML BTRHEOM CEMAGREFIMGIBB Two-Point Mod Slump*

BML 0.84 0.98 0.96 0.58 -0.41

BTRHEOM 0.91 0.86 0.82 -0.29

CEMAGREFIMG0.98 0.75 -0.41

IBB 0.65 -0.40

Two-Point -0.15

Slump

Note: * no changes from

Table 13 because no data is available for Mixture # 4 in the modified slump

A second objective was to determine the relationships between the Bingham constants

measured by pairs of rheometers and results of the slump and modified slump test. Only 12

data points were available in each case (fewer from the CEMAGREF-IMG), and no mixture

was repeated. Therefore, there was an insufficient number of results for fitting any other than

a linear relationship. The computed regression coefficients are shown in Table 15 and Table

16. For example, in Table 15, the yield stress equation relating BML and BTRHEOM

rheometers is:

BML Yield stress = 0.50 *(BTRHEOM Yield stress) –122.0 ( 42 )
47

For those rheometers that determine the Bingham constants in fundamental units, the ideal

case would be for the slope coefficient to be 1 or close to it, and the intercept coefficient to

be zero or near zero, i.e., the different tests would give similar results. Clearly, this is not the

situation in most cases. The significance of the results, the confidence with which they can be

used, and the possible reasons for the differences, are discussed in the next section.

Table 15: Between-rheometer linear correlation functions for the yield stress. The

rheometers in the column head are Y and those in the row head are X. In each cell the

coefficients of the equation Y=AX +B are shown. The rheometers are listed in

alphabetical order.

A;B BML

[Pa]

BTRHEOM

[Pa]

CEMAGREF

-IMG

[Pa]

IBB

[N×m]

Two-Point

[Pa]

Slump

[mm]

BML

[Pa]

1.85; 300.9 1.98; 179.89 0.008;0.334 1.010; 7.007 –0.18;

248.2

BTRHEOM

[Pa]

0.50; -122.0 0.974; -93.6 0.004; -0.91 0.54; -153.9 -0.09; 273.0

CEMAGREFIMG

[Pa]

0.45; -40.7 0.91; 204.7 0.0049;-0.824 0.56; -99.79 -0.09; 261.1

IBB

[N×m]

79.7; 126.2 155.3; 504.3 163.4; 316.9 95.4; 75.4 -15.8; 231.6

Two-Point

[Pa]

0.87; 46.3 1.72; 338.3 1.75; 194.6 0.008;0.114 -0.17; 244.9

Slump

[mm]

-5.59; 1387.3 -10.77; 2942.2 -11.1; 2898.1 -0.063; 14.7 -5.99; 1466.8

Table 16: Between-rheometer linear correlation functions for the plastic viscosity (all

data available are used). The rheometers in the column head are Y and those in the row

head are X. In each cell the coefficients of the equation Y=AX +B are shown. The

rheometers are listed in alphabetical order.

A;B BML

[Pa×.s]

BTRHEOM

[Pa×s]

CEMAGREF

-IMG

[Pa×s]

IBB

[N×m×s]

Two-Point

[Pa×s]

Mod Slump

[Pa×s]

BML

[Pa×s]

1.202; 6.20 2.06; -31.19 0.089; 5.3 0.37; 13.84 -0.08; 51.6

BTRHEOM

[Pa×s]

0.59; 11.16 1.01; -9.91 0.056; 6.07 0.36; 7.20 -0.11; 75.24

CEMAGREFIMG

[Pa×s]

0.47; 15.7 0.81; 15.50 0.081; 5.36 0.35; 12.68 -0.039; 51.7

IBB

[N×m×s]

10.37; -50.9 13.2; -62.60 11.9; -62.9 4.43; -10.97 -0.009; 10.5

Two-Point

[Pa×s]

0.926; 20.06 1.87; 9.88 1.59; -6.19 0.0961; 6.64 -0.034; 36.8

Mod Slump

[Pa×s]

-2.03; 263.1 -0.79; 233.3 -1.79; 269.9 -16.4; 331.1 -0.69; 210.9
48

0

200

400

600

800

1000

1200

1400

0 500 1000 1500 2000 2500

yield stress, BTRHEOM(Pa)

yield stress, BML(Pa)

data points

Reg Line

95% conf L

95% conf H

Equil. Line

0

500

1000

1500

2000

2500

0 200 400 600 800 1000

yield stress, BML(Pa)

yield stress, BTRHEOM(Pa)

0

2 0

4 0

6 0

8 0

100

120

140

160

180

0 5 0 100 150 200

plastic viscosity, BTRHEOM(Pa.s)

plastic viscosity, BML(Pa.s)

0

5 0

100

150

200

0 2 0 4 0 6 0 8 0 100 120

plastic viscosity, BML(Pa.s)

plastic viscosity, BTRHEOM(Pa.s)

Figure 29: Comparison between BML and BTRHEOM
49

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

yield stress, Cemagref(Pa)

yield stress, BML(Pa)

0

500

1000

1500

2000

2500

0 200 400 600 800

yield stress, BML(Pa)

yield stress, Cemagref(Pa)

data points

Reg Line

95% conf L

95% conf H

Equil. Line

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

0 1 0 2 0 3 0 4 0 5 0

plastic viscosity, BML(Pa.s)

plastic viscosity, Cemagref(Pa.s)

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

plastic viscosity, Cemagref(Pa.s)

plastic viscosity, BML(Pa.s)

Figure 30: Comparison between BML and CEMAGREF-IMG
50

0

200

400

600

800

1000

1200

1400

0 2 4 6 8 1 0 1 2

yield stress, IBB(Nm)

yield stress, BML(Pa)

0

2

4

6

8

1 0

1 2

1 4

0 200 400 600 800 1000

yield stress, BML(Pa)

yield stress, IBB(Nm)

data points

Reg Line

95% conf L

95% conf H

0

2

4

6

8

1 0

1 2

1 4

1 6

1 8

2 0

0 2 0 4 0 6 0 8 0 100 120

plastic viscosity, BML(Pa.s)

plastic viscosity, IBB(Nm.s)

0

2 0

4 0

6 0

8 0

100

120

140

0 5 1 0 1 5

plastic viscosity, IBB(Nm.s)

plastic viscosity, BML(Pa.s)

Figure 31: Comparison between BML and IBB
51

0

200

400

600

800

1000

1200

1400

0 200 400 600 800 1000

yield stress, BML(Pa)

yield stress, 2 point(Pa)

0

200

400

600

800

1000

1200

1400

0 200 400 600 800 1000 1200

yield stress, 2 point(Pa)

yield stress, BML(Pa)

data points

Reg Line

95% conf L

95% conf H

Equil. Line

0

5 0

100

150

200

0 2 0 4 0 6 0 8 0 100

plastic viscosity, 2 point(Pa.s)

plastic viscosity, BML(Pa.s)

0

2 0

4 0

6 0

8 0

100

120

0 2 0 4 0 6 0 8 0 100 120

plastic viscosity, BML(Pa.s)

plastic viscosity, 2 point(Pa.s)

Figure 32: Comparison between BML and Two-Point test
52

0

500

1000

1500

2000

2500

3000

0 500 1000 1500 2000 2500

yield stress, Cemagref(Pa)

yield stress, BTRHEOM(Pa)

0

500

1000

1500

2000

2500

3000

0 500 1000 1500 2000 2500

yield stress, BTRHEOM(Pa)

yield stress, Cemagref(Pa)

data points

95% conf L

95% conf H

Reg Line

Equil. Line

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

100

0 2 0 4 0 6 0 8 0

plastic viscosity, BTRHEOM(Pa.s)

plastic viscosity, Cemagref(Pa.s)

0

2 0

4 0

6 0

8 0

100

120

0 2 0 4 0 6 0

plastic viscosity, Cemagref(Pa.s)

plastic viscosity, BTRHEOM(Pa.s)

Figure 33: Comparison between BTRHEOM and CEMAGREF-IMG
53

0

500

1000

1500

2000

2500

3000

0 2 4 6 8 1 0 1 2

yield stress, IBB(Nm)

yield stress, BTRHEOM(Pa)

0

2

4

6

8

1 0

1 2

1 4

0 500 1000 1500 2000 2500

yield stress, BTRHEOM(Pa)

yield stress, IBB(Nm)

data points

Reg Line

95% conf L

95% conf H

0

5

1 0

1 5

2 0

2 5

0 5 0 100 150 200

plastic viscosity, BTRHEOM(Pa.s)

plastic viscosity, IBB(Nm.s)

0

5 0

100

150

200

250

0 5 1 0 1 5

plastic viscosity, IBB(Nm.s)

plastic viscosity, BTRHEOM(Pa.s)

Figure 34: Comparison between BTHEOM and IBB
54

0

200

400

600

800

1000

1200

1400

0 500 1000 1500 2000 2500

yield stress, BTRHEOM(Pa)

yield stress, 2 point(Pa)

0

500

1000

1500

2000

2500

3000

0 200 400 600 800 1000 1200

yield stress, 2 point(Pa)

yield stress, BTRHEOM(Pa)

data points

Reg Line

95% conf L

95% conf H

Equil. Line

0

5 0

100

150

200

250

0 2 0 4 0 6 0 8 0

plastic viscosity, 2 point(Pa.s)

plastic viscosity, BTRHEOM(Pa.s)

0

2 0

4 0

6 0

8 0

100

120

0 5 0 100 150 200

plastic viscosity, BTRHEOM(Pa.s)

plastic viscosity, 2 point(Pa.s)

Figure 35: Comparison between BTRHEOM and Two-Point test
55

Figure 36: Comparison between IBB and CEMAGREF-IMG

0

2

4

6

8

1 0

1 2

1 4

0 500 1000 1500 2000 2500

yield stress, Cemagref(Pa)

yield stress, IBB(Nm)

0

500

1000

1500

2000

2500

3000

0 2 4 6 8 1 0 1 2

yield stress, IBB(Nm)

yield stress, Cemagref(Pa)

data points

Reg Line

95% conf L

95% conf H

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

100

0 2 4 6 8 1 0 1 2

plastic viscosity, IBB(Nm.s)

plastic viscosity, Cemagref(Pa.s)

0

2

4

6

8

1 0

1 2

1 4

0 2 0 4 0 6 0 8 0

plastic viscosity, Cemagref(Pa.s)

plastic viscosity, IBB(Nm.s)
56

0

200

400

600

800

1000

1200

1400

0 500 1000 1500 2000 2500

yield stress, Cemagref(Pa)

yield stress, 2 point(Pa)

0

500

1000

1500

2000

2500

3000

0 200 400 600 800 1000 1200

yield stress, 2 point(Pa)

yield stress, Cemagref(Pa)

data points

Reg Line

95% conf L

95% conf H

Equil. Line

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

100

0 1 0 2 0 3 0 4 0

plastic viscosity, 2 point(Pa.s)

plastic viscosity, Cemagref(Pa.s)

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

plastic viscosity, Cemagref(Pa.s)

plastic viscosity, 2 point(Pa.s)

Figure 37: Comparison between CEMAGREF-IMG and Two-Point test
57

0

2

4

6

8

10

12

14

0 200 400 600 800 1000 1200

yield stress, 2 point(Pa)

yield stress, IBB(Nm)

data points

Reg Line

95% conf L

95% conf H

0

200

400

600

800

1000

1200

1400

0 2 4 6 8 1 0 1 2

yield stress, IBB(Nm)

yield stress, 2 point(Pa)

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

100

0 2 4 6 8 1 0 1 2 1 4

plastic viscosity, IBB(Nm.s)

plastic viscosity, 2 point(Pa.s)

0

5

1 0

1 5

2 0

2 5

0 2 0 4 0 6 0 8 0 100

plastic viscosity, 2 point(Pa.s)

plastic viscosity, IBB(Nm.s)

Figure 38: Comparison between IBB and Two-Point test
58

0

2 0

4 0

6 0

8 0

100

120

140

160

180

0 2 0 4 0 6 0 8 0 100

plastic viscosity, 2 point(Pa.s)

plastic viscosity, BML(Pa.s)

data points

Linear Reg.

95% conf L

95% conf H

Equil. Line

0

2 0

4 0

6 0

8 0

100

120

0 2 0 4 0 6 0 8 0 100 120

plastic viscosity, BML(Pa.s)

plastic viscosity, 2 point(Pa.s)

Figure 39: Comparison of plastic viscosities between BML,

BTRHEOM and Two-Point test when the data points from

Mixture #4 were omitted.

0

5 0

100

150

200

250

0 2 0 4 0 6 0 8 0

plastic viscosity, 2 point(Pa.s)

plastic viscosity, BTRHEOM(Pa.s)

data points

Reg Line

95% conf L

95% conf H

Equil. Line

0

2 0

4 0

6 0

8 0

100

120

0 5 0 100 150 200

plastic viscosity, BTRHEOM(Pa.s)

plastic viscosity, 2 point(Pa.s)
59

0

5

10

15

20

25

0 20 40 60 80 100

plastic viscosity, 2 point(Pa.s)

plastic viscosity, IBB(Nm.s)

data points

Reg Line

95% conf L

95% conf H

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14

plastic viscosity, IBB(Nm.s)

plastic viscosity, 2 point(Pa.s)

Figure 40: Comparison of plastic viscosities between IBB

and Two-Point test. The data from Mixture #4 were

omitted.
60

5. Discussion

5.1. Comments on correlations between pairs of rheometers

5.1.1. Linear regression or not?

It is clear from the results that there is some correlation between the values given by the

different rheometers for both yield stress and plastic viscosity. The correct correlation

function between any two instruments should be of the type Y= X (yield stress according to

one rheometer Y = yield stress according to another rheometer X; similarly for plastic

viscosity). The slope should be 1 and the line should go through the origin. This is obviously

not the case for most pairs of rheometers (Table 15 and Table 16 or Figure 29 to Figure 40).

Therefore, some effects are not fully taken into account in the calculation of the yield stress

and plastic viscosity from the raw data from the rheometers. This leads to erroneous values

for yield stress and plastic viscosity. Without knowledge of the source of the errors or the

availability of a standard material or rheometer, it is impossible to determine the correct

correlation between the rheometers.

As the results presented are not related by a function Y=X, the question is raised, could we

approximate the relationship between rheometers to allow users to compare their results? For

this, a linear relationship was selected, but the coefficients should be used with caution. The

reason is that the small number of points available does not allow a clear selection of the

correct function. Most of all, the R coefficient should be used with caution. It implies several

hypotheses that were not tested during the tests, mainly that the distribution of the results

follows a normal distribution for each apparatus. Moreover, the value against which R must

be compared depends on the number of points considered, and this number is not the same

for all the apparatus (between 7 and 12 data points).

5.1.2. Critical review of R

In Table 12 to Table 14, the value of R for the correlations are listed for each pair of

rheometers. To be correctly interpreted, the value of R (or R2) must be compared to a

reference value that depends on the number of points used for the correlation. In our case,

depending on the rheometers compared, this number ranges from 7 to 12.

For 12 points, at the 1 % level (α=0.01, ν=10), the reference value of R is 0.7079, i.e.

R2=0.5011 (see Table 17).
61

Table 17 Critical values for the correlation coefficient R of a sample extracted from a

normal distributed population. a is the probability, and n = n-2, n being the number of

points. If the calculated value of R is higher than the reference value shown in the table,

there is a probability a that X and Y are dependent.

 a

n 

0.1 0.05 0.01

5 0.6694 0.7545 0.8745

6 0.6215 0.7067 0.8343

7 0.5822 0.6664 0.7977

8 0.5494 0.6319 0.7646

9 0.5214 0.6021 0.7348

10 0.4973 0.5760 0.7079

Table 12 to Table 14 show that these levels are exceeded by all correlations except those

involving the modified slump. There is no correlation between modified slump and plastic

viscosity and this test will not be considered further. However, slump correlates well with

yield stress, confirming the observation originally made by Tattersall and Banfill [16].

5.2. Discussion on discrepancies on absolute values

When attempting to compare the absolute values measured with the various rheometers, an

immediate conclusion is that the instruments fall into two groups consisting of (a) the

BTRHEOM and CEMAGREF-IMG, and (b) the Two-Point and BML. The agreement is

excellent within group (a), acceptable within group (b), but less satisfactory between the two

groups. In one sense this is encouraging because of the level of agreement between

instruments whose principles of operation differ. The BTRHEOM is essentially a parallel

plate rheometer, whereas the CEMAGREF-IMG is a coaxial cylinder rheometer. The TwoPoint consists of a blade rotating in a concrete container whereas the BML has a coaxial

cylinder rheometer. However, better agreement between the BML and the CEMAGREFIMG, both coaxial cylinder instruments, would have been expected. Plastic viscosity agrees

adequately but the difference in yield stress is large.

In a perfect world, all rheometers would give the same values for yield stress and for plastic

viscosity for a given concrete. Although there is a high correlation between the rheometers,

the absolute values are not identical. Discussions were conducted on this topic and some

hypotheses were put forward, which need to be tested through further research. The

hypotheses are:

• Each rheometer was calibrated using a different method. Some were calibrated using oil

as a reference material, while others were calibrated through the load cell used to
62

measure the torque. Calculations to convert torque and rotational speed to plastic

viscosity and yield stress in fundamental units rely on known equations for specific

geometries. Most equations assume that the flow between the moving parts is linear. This

assumption was not always verified in practice.

• The shearing surfaces are usually designed to avoid slippage. Nevertheless, it was not

always possible to avoid slippage in the tests reported here. Slippage might explain some

lower values as compared to a rheometer with no slippage. It is relevant that Mannheimer

has pointed out that for cement pastes [30], slippage can have a significant effect on the

measured yield stress. Further, the gap between parts of a rheometer must be high as

compared to the maximum size of particles. If this condition is not fulfilled, confinement

effects may occur. These issues are discussed in Appendix F.

• The CEMAGREF-IMG has a seal at the bottom to avoid concrete seeping under the

moving cylinder. The seal friction is calibrated using an empty rheometer. A question

that could be raised is whether the pressure on the seal exerted by the concrete might alter

the seal friction. Calculations presented in Appendix G show that a very pessimistic

assumption on the nature of the friction at the seal level only leads to an overestimation

of the yield stress by 40 Pa to 50 Pa. This is far from the difference shown between the

CEMAGREF-IMG and the other instruments.

• The other instrument that has a seal is the BTRHEOM. This instrument is calibrated

using water before loading the instrument with concrete. Extensive investigations [11]

were conducted to evaluate the difference between the seal friction in the presence of

concrete (where cement grout fills the gap between seal and container) from that in the

presence of water. Further, owing to the dimensions of this apparatus, concrete pressure

is not likely to have significant influence on seal friction. So the discrepancy could not be

attributed to an incorrect estimate of seal friction in the BTRHEOM.

5.3.Correlation between the slump and the yield stress

It was stated earlier and it can be seen from Figure 25 that slump is correlated with yield

stress. Several attempts to determine an equation to relate the two entities can be found in

the literature [26, 31, 32, 33]. Some of the equations are based on finite element simulations

of slump cone tests [31, 32] while others are based on the fitting of sets of data [26, 33].

They all have the common form:

C

B

A S

+

−

=

( )

0

r

t ( 43 )

where

S is the slump in mm

τ0 is the shear yield stress in Pa

ρ is density in kg/m3

A, B, C are constants to be determined either by fitting data or by simulation
63

The two cases we will compare with our data were developed by Hu et al. [31] and

Kurokawa [32]. In these cases the constants are:

Hu’s constants: A = 300; B = 270 and C = 0

Kurakawa’s constants: A = 300; B = 303 and C = 0.

These constants were deduced from finite-element calculations based on the equilibrium of

the concrete sample at the end of the slump test, and not on fit of experimental data.

Figure 41 shows the data obtained in this study compared with the Hu and Kurokawa

equations. It seems that these equations are on the high end of the data obtained in this study.

A: Model of Kurakawa

0

500

1000

1500

2000

2500

0 500 1000 1500 2000 2500

Yield stress measured [Pa]

Yield stress Theo [Pa]

BML

BTRHEOM

Cemagref

2-point

45 line

B: Model of Hu

0

500

1000

1500

2000

2500

0 500 1000 1500 2000 2500

Yield stress measured [Pa]

Yield stress Theo [Pa]

BML

BTRHEOM

Cemagref

2-point

45 line

Figure 41: Comparison of measured and predicted yield stress according to equations

developed by Hu and Kurakawa
64

6. Summary of findings

This report relates the results obtained from the first ever systematic comparison of concrete

rheometers. It was carried out in France in October 2000.

A series of twelve concrete mixtures was tested in five rheometers. The mixtures had slumps

ranging from 90 mm to 235 mm, but more importantly, they had a wide range of

combinations of yield stress and plastic viscosity. The rheometers were all rotational, but

were based on different principles and could be grouped as follows:

• · Coaxial: BML and CEMAGREF-IMG

• · Parallel plate: BTRHEOM

• · Mixing action with an impeller: IBB and Two-Point apparatus

There were widely different geometries both within and between groups.

It was found that the rheometers gave different values of the Bingham constants of yield

stress and plastic viscosity, even for those instruments that give these directly in fundamental

units. However, it was found that:

• All the mixtures were ranked statistically in the same order by all the rheometers for both

yield stress and for plastic viscosity.

• The degree of correlation of both yield stress and plastic viscosity measurements between

any pair of rheometers was reasonably high. Relationships with 95 % confidence levels

have been proposed to relate measurements with one rheometer to those with another.

• Differences in absolute values given by the various rheometers may be attributed to

several causes, like slip at the concrete/wall interface, or confinement of concrete

between moving parts of the rheometers (Appendix F). Further research is needed to

quantify and, if necessary, to correct these effects.

• The slump test correlates well with the yield stress as measured with any of the

rheometers

• The slumping time measured with the modified slump test does not correlate with the

plastic viscosity. Therefore, it was concluded that this test is not useful for concretes

having a relatively narrow range of plastic viscosities such as those investigated in this

project.

• One future utilization of concrete rheology is to predict the flow kinematics of concrete

operations. For this purpose, it is necessary to have sound basic rheological parameters.

This report has shown that rheometers could be used to provide this information.

The fact that findings (1) and (2) above apply to instruments operating on different principles

and with a range of geometries is encouraging and an important step forward for the subject

as a whole. All the rheometers are therefore able to describe the rheology or flow of fresh
65

concrete, and the correlations obtained will assist in the analysis and comparison of results

from different rheometers in different laboratories on different concretes. There are, however,

some consistent differences that cannot be unambiguously explained at this point. Some

hypotheses were discussed but further research is needed.

There is a great need for standardization of rheological measurements on concrete. This study

is the first step in attempting to compare methodologies.

7. Future work

This report answered some questions but raised many more. Further research is needed to

address the issues raised.

The authors suggest that the following points be considered in a new series of tests:

• A wider range of mixtures, to include self-compacting concretes.

• A wider range of plastic viscosities.

• Concretes with similar rheological properties designed with a wide range of aggregate

sizes and shapes (crushed and round).

• A set with repetition of mixtures, to give greater confidence in the correlations between

results from the various test systems, and perhaps identifying non-linear relationships if

these exist.

• Tests and analysis to explain the consistent difference between the results of those

instruments that give values of the Bingham constants in fundamental units. This would

include consideration of calibration, wall slippage and volumetric confinement. It would

be beneficial if some progress could be made with this before further comparative tests

are made.

• Apply numerical simulations to exhibit the various artifacts that can occur in different

rheometers.

• Investigate the possibility of developing a standard material for calibration of rheometers.
66

8. References

1 Hu, C., “Rhéologie des bétons fluides,” Etudes et Recherches des Laboratoires des

Ponts et Chaussées, OA 16, 203 p., Paris, France, 1995

2 Ferraris C., Brower L., Ozyildirim C., Daczko J., “Workability of Self-compacting

Concrete,” Symp. Proc. of PCI/FHWA/FIB Int. Symposium on ‘High Performance

Concrete: The Economical Solution for Durable Bridges and Transportation

Structures” ,Orlando (FL) Sept 25-27, pp. 398-407, 2000

3 de Larrard F., “ Why rheology matters,” Concrete International, vol. 21 #8, pp. 79-81,

1999

4 Tattersall, G.H., The workability of concrete, A Viewpoint Publication, Cement and

Concrete Association, 1976

5 Urano S., Hashimoto C., Tsuji Y., “Evaluation of flow of self-compacting concrete by

visualization technique,” Proc. 1st Inter. RILEM Symp. On ‘Self-compacting

Concrete’, Sweden, PROC 7 pp. 25-34, 1999

6 Ferraris, C.F., “Measurement of the Rheological Properties of High Performance

Concrete: State of the Art Report,” Journal of Research of NIST, vol. 104 #5, pp.

461-478, 1999

7 Hackley V. A., Ferraris C. F., “Guide to Rheological Nomenclature: Measurements in

Ceramic Particulate Systems,” NIST Special Publication 946, February 2001

8 Wallevik O.H., “The Rheology of Fresh Concrete and its Application on Concrete

with and without Silica Fume.” Dr.ing. thesis 1990:45, NTH Trondheim. p. 185 (in

Norwegian), 1990

9 Wallevik O.H., Gjorv, O.E., “Development of a Coaxial Cylinder Viscometer for

Fresh Concrete,” Properties of Fresh Concrete, proceedings of the Rilem Colloquium,

Chapman & Hall, Hanover, October, 1990, pp. 213-224

10 de Larrard, F., Szitkar J.-C., Hu, C., Joly M., “Design of a Rheometer for Fluid

Concretes,” RILEM Workshop Special Concretes – Workability and Mixing, 201-

208, 1993

11 de Larrard, F., Sedran, T., Hu, C., Szitkar, J.C., Joly, M., Derkx, F., “Evolution of the

Workability of Superplasticized Concretes: assessment with BTRHEOM Rheometer,”

RILEM International Conference on Production Methods and Workability of

Concrete, RILEM Proceedings 32, , Glasgow, Scotland, June 3-5, pp. 377-388, 1996.

12 Beaupré, D., “Rheology of High Performance Shotcrete,” Ph. D. Thesis Uni. Of

British Columbia (Canada), 1994
67

13 Domone P.L.J., Xu Yongmo, Banfill P.F.G., “Developments of the Two-Point

workability test for high-performance concrete,” Magazine of Concrete Research, vol.

51, pp. 181-190, 1999

14 Sedran T., de Larrard F., “BétonlabPro 2 - Logiciel de formulation de bétons -

Version exécutable sous Windows” (BétonlabPro 2 – Software for computer-aided

concrete mixture-proportioning – Ms. Windows version), Presses de l'Ecole Nationale

des Ponts et Chaussées, Paris, June, 2000

15 Vandanjon P.O., “Evaluation et utilisation du banc d'analyse granulométrique, un

appareil de mesure de l'homogénéité des mélanges (Evaluation and use of the

Automatic Fresh Mix Analyser, an apparatus for mix homogeneity assessment),”

Bulletin des Laboratoires des Ponts et Chaussées, No. 222, pp. 3-12, July-August,

1999.

16 Tattersall, G.H., Banfill, P.F.G., The rheology of fresh concrete, Pitman, London,

356, 1983

17 Barnes H.A., Hutton, J.F., Walters, K., “An introduction to Rheology,” Elsevier, p.

10, p. 128, p. 141, pp. 148-149 and p.156, 1989

18 Malvern L.E., Introduction to the Mechanics of a Continuous Medium, Prentice Hall

Inc, , p. 214 and p. 357, 1969

19 Banfill, P.F.G., “A Coaxial Cylinders Viscometer for Mortar: Design and

Experimental Validation,” Rheology of fresh cement and concrete, E. & F.N. Spon,

Liverpool, pp. 217-227, 1990

20 De Larrard F., Ferraris C. F. and Sedran T., “Fresh Concrete: a Herschel-Bulkley

Material,” Technical note, Materials and Structures, Vol. 31, pp. 494-498, AugustSeptember, 1998.

21 Coussot, P., “Rheologie des boues et laves torrentielles - Etudes de dispersions et

suspensions concentrées,” Thèse de doctorat de l'institut National Polytechnique de

Grenoble, et Etudes du Cemagref, série Montagne n°5, 418 p, 1993

22 Tattersall, G.H., Bloomer, S.J., “Further development of the Two-Point test for

workability and extension of its range,” Magazine of Concrete Research 31: pp. 202-

210, 1979

23 Domone, P.L.J., Xu, Y., Banfill, P.F.G. , “Developments of the Two-Point

workability test for high-performance concrete,” Magazine of Concrete Research vol.

51, pp. 171-179, 1999

24 Ferraris, C.F., de Larrard, F. “Modified Slump Test to Measure Rheological

Parameters of Fresh Concrete,” Cement, Concrete and Aggregates, Vol. 20 #2, pp.

241-247, 1998
68

25 De Larrard, F., Hu, C.,Sedran, T., Sitzkar, J.C., Joly, M., Claux, F., Derkx F., “A New

Rheometer for Soft-to-Fluid Fresh Concrete,” ACI Materials Journal, Vol. 94, No. 3,

pp. 234-243, 1997

26 Ferraris, C.F., F. de Larrard,F., “Testing and Modelling of Fresh Concrete Rheology,”

NISTIR 6094, 1998

27 Chidiac, S.E., Maadani, O., Razaqpur, A.G., and Mailvaganam, N.P., “Controlling

the quality of fresh concrete A new approach,” Magazine of Concrete Research, vol.

52 (5) pp.353-364, 2000

28 Saporta, G., Probabilités, analyse des données et statistiques, Editions TECHNIP,

1990 (in French)

29 Meyer, S.L., Data Analysis for Scientists and Engineers, John Wiley& Sons, p. 143,

1975

30 Mannheimer, R.J., “Effect of slip on flow properties of oilwell cement slurries,” Oil

and Gas Journal, Dec 5, pp. 144-147, 1983

31 Hu, C., de Larrard, F., Sedran, T., Boulay, C., Bosc, F., Deflorenne, F., “Validation of

BTRHEOM, the new rheometer for soft-to-fluid concrete,” Materials and Structures,

Vol. 29, No. 194, pp. 620-631, 1996

32 Kurokawa, Y., Tanigawa, Y., Mori, H., Komura, R., “A Study on the Slump Test and

Slump-Flow Test of Fresh Concrete,” Transactions of the Japan Concrete Institute,

vol. 16, pp. 25-32, 1994

33 Sedran R., “Rheologie et rhéométrie des bétons. Application aux bétons

autonivelants,” Thèse de l'ENPC (“Rheometry and rheology of concrete. An

application to Self Compacting Concrete,” PhD Thesis), 220 p, Mars, 1999
A - 69

APPENDIXES
A - 70
A - 71

TABLE OF CONTENTS

APPENDIX A: PICTURES OF RHEOMETERS AND THE LCPC FACILITY......................................................73

APPENDIX B: PICTURES FROM THE SLUMP TESTS...............................................................................................79

APPENDIX C: DATA FROM THE RHEOMETERS .......................................................................................................85

DATA AND GRAPHS FROM THE BML........................................................................................................................................85

DATA AND GRAPHS OBTAINED USING THE BTRHEOM........................................................................................................89

DATA AND GRAPHS OBTAINED USING THE CEMAGREF-IMG............................................................................................94

DATA AND GRAPHS OBTAINED USING THE IBB................................................................................................................... 117

DATA AND GRAPHS OBTAINED USING THE TWO-POINT TEST ............................................................................................ 122

APPENDIX D: CALIBRATION REPORT FOR THE CEMAGREF-IMG..............................................................125

APPENDIX E: CALCULATION OF THE KENDALL COEFFICIENT OF CONCORDANCE......................131

APPENDIX F: ARTIFACTS IN RHEOLOGICAL MEASUREMENTS ..................................................................133

SIZE OF TESTED SPECIMEN...................................................................................................................................................... 133

SLIP AT THE BOUNDARIES OF THE SPECIMEN ....................................................................................................................... 133

WALL EFFECT ........................................................................................................................................................................... 136

ARTIFACTS AND RHEOMETERS – A CRITICAL REVIEW....................................................................................................... 140

APPENDIX G: SEAL FRICTION IN CEMAGREF-IMG TEST: EFFECT OF CONCRETE HEIGHT........143

INTRODUCTION ........................................................................................................................................................................ 143

QUANTITATIVE ANALYSIS....................................................................................................................................................... 143

CONCLUSION ............................................................................................................................................................................ 145

REFERENCES FOR THE APPENDIXES .........................................................................................................................147
A - 72
A - 73

Appendix A: Pictures of Rheometers and the LCPC Facility

BML
A - 74

BTRHEOM
A - 75

CEMAGREF-IMG
A - 76

IBB
A - 77

Two-point test
A - 78

Batch plant

Transportation of concrete to the rheometers
A - 79

Appendix B: Pictures from the slump tests

The slump tests, depicted here, were carried out at the same time as the concrete was being tested

in the rheometers.

Mixture #1

Mixture #2
A - 80

Mixture #3

Mixture #4
A - 81

Mixture #5

Mixture #6
A - 82

Mixture #7

Mixture #8
A - 83

Mixture #9

Mixture #10
A - 84

Mixture #11

Mixture #12
A - 85

Appendix C: Data from the rheometers

Data and graphs from the BML

All the mixes were run twice and are shown here and in the graphs, but only the first run was

used in the report to compare with the other rheometers.

Velocity Mix-01 Mix-02 Mix-03 Mix-04 Mix-05 Mix-06 Mix-07 Mix-08 Mix-09 Mix-10 Mix-11 Mix-12

(rev/s) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm)

0,46 21,92 No 2,84 No 14,18 No 19,01 No 24,83 No 6,85 No 5,00 No 12,82 No 3,51 No 8,19 No 9,80 No 12,93 No

0,4 20,17 No 2,64 No 12,87 No 17,66 No 21,02 No 6,35 No 4,25 No 11,98 No 3,23 No 7,43 No 9,59 No 12,22 No

0,34 19,11 No 2,34 No 11,98 No 16,66 No 20,23 No 5,42 No 3,73 No 11,80 No 3,01 No 7,01 No 8,98 No 11,64 No

0,28 16,92 No 2,09 No 10,78 No 15,64 No 18,45 No 4,84 No 3,32 No 11,32 No 2,83 No 6,16 No 8,41 No 11,14 No

0,21 15,23 No 1,86 No 9,38 No 14,92 No 18,19 No 4,25 No 3,05 No 11,07 No 2,60 No 5,75 No 8,13 No 10,55 No

0,15 13,99 No 1,63 No 8,34 No 13,71 No 15,80 No 3,59 No 2,44 No 10,62 No 2,34 No 5,26 No 7,87 Yes 10,01 No

0,09 13,13 Yes 1,43 Yes 7,69 Yes 14,03 Yes 14,64 No 3,07 Yes 1,95 No 10,11 No 2,12 No 4,66 No 7,69 Yes 9,18 No

0,3 17,1 2,0 10,6 15,1 18,6 5,0 3,4 11,6 2,7 6,4 8,2 11,6

VelocityMix-01B Mix-02B Mix-03B Mix-04B Mix-05B Mix-06B Mix-07B Mix-08B Mix-09B Mix-10B Mix-11B Mix-12B

(rev/s) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm) (Nm)

0,46 2,79 No 13,46 No 16,97 No No 7,33 No 5,13 No 13,28 No 3,54 No 8,38 No 11,08 No 14,20 No

0,4 2,45 No 12,01 No 15,69 No No 6,45 No 4,54 No 12,74 No 3,17 No 7,49 No 10,26 No 13,63 No

0,34 2,19 No 11,63 No 15,02 No No 5,47 No 3,96 No 11,68 No 2,94 No 6,76 No 9,62 No 13,13 No

0,28 1,97 No 10,12 No 13,66 No No 5,09 No 3,42 No 11,52 No 2,76 No 6,21 No 9,22 No 12,39 No

0,21 1,81 No 9,14 No 13,69 No No 4,54 No 2,90 No 11,17 No 2,47 No 5,67 No 8,83 No 11,89 No

0,15 1,51 No 7,96 No 12,74 Yes No 3,88 No 2,63 No 10,20 No 2,34 No 4,99 No 8,77 Yes 11,14 No

0,09 1,40 Yes 7,25 Yes 12,51 Yes No 3,29 Yes 2,13 No 10,03 No 2,12 No 4,37 No 8,60 Yes 10,30 No

0,3 2,0 10,2 13,5 5,2 3,5 12,0 2,7 6,2 8,9 12,9
A - 86

y = 25,99x +

9,92

R 2 = 0,99

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-01

Control

Mix-01

y = 3,95x + 1,02

R 2 = 1,00

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-02

Control

Mix-02B

Control

Mix-02

y = 18,77x +

5,50

R 2 = 1,00

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-03

Control

Mix-03B

Control

Mix-03

y = 16,37x +

11,25

R 2 = 0,99

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-04

Control

Mix-04B

Control

Mix-04

y = 25,30x +

11,99

R 2 = 0,92

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-05

Control

Mix-05

y = 10,62x +

1,96

R 2 = 0,99

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-06

Control

Mix-06B

Control

Mix-06

y = 7,28x + 6,52

R 2 = 0,97

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-11

Control

Mix-11B

Control

Mix-11

y = 9,63x + 8,44

R 2 = 0,99

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-12

Control

Mix-12B

Control

Mix-12

y = 7,71x + 1,26

R 2 = 0,98

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-07

Control

Mix-07B

Control

Mix-07

y = 6,64x + 9,56

R 2 = 0,97

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-08

Control

Mix-08B

Control

Mix-08

y = 3,65x + 1,80

R 2 = 1,00

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-09

Control

Mix-09B

Control

Mix-09

y = 9,30x + 3,79

R 2 = 0,99

0

5

10

15

20

25

0 0,25 0,5

Velocity (rev/s)

Torque (Nm)

Mix-10

Control

Mix-10B

Control

Mix-10
A - 87

The following table gives the summary of the calculated results.

Mix Test G-value H-value rd G d H Seg. Yield Pl. Visc Time Date Time

no. no. (Nm) (Nm s) (Nm) (Nm s) (Pa) (Pa s) (min) (dd/mm/yy) (hh/mm/ss)

1 1 9,81 25,93 0,997 0,28 0,29 4 738 114,1 1 32 24/10/2000 10:17:26

2 10,13 21,21 0,991 0,37 0,39 6 761 93,3 1 45 24/10/2000 10:30:32

2 1 1,01 3,95 0,999 0,06 0,07 1 1 76 17,4 1 24/10/2000 12:04:21

2 0,90 3,91 0,995 0,14 0,15 6 68 17,2 1 24/10/2000 12:13:45

3 1 5,42 18,72 0,999 0,16 0,17 6 408 82,4 1 24/10/2000 14:51:54

2 5,36 17,22 0,994 0,33 0,34 5 403 75,8 1 24/10/2000 14:59:40

4 1 11,17 16,36 0,997 0,22 0,24 7 840 72,0 1 24/10/2000 16:55:39

2 10,30 13,74 0,968 0,81 0,85 7 774 60,5 1 24/10/2000 17:03:33

5 1 12,11 24,64 0,974 0,70 0,73 6 911 108,4 1 25/10/2000 09:56:18

2 Error 45,11 33,13 0,956 1,07 1,13 1 0 3391 145,8 1 25/10/2000 10:03:11

6-SCC 1 1,91 10,61 0,997 0,16 0,17 3 139 45,0 1

25/10/2000 12:10:45

2 2,13 10,69 0,990 0,33 0,35 6 155 45,4 1 25/10/2000 12:18:30

3 Thixotropy 2,19 14,58 0,997 0,19 0,20 6 159 61,4 4 25/10/2000 12:21:58

7 1 1,24 7,69 0,994 0,19 0,20 6 90 32,7 1 25/10/2000 15:13:22

2 1,31 7,93 0,996 0,16 0,17 7 98 34,9 1 25/10/2000 15:18:43

3 Thixo 1,30 10,34 0,998 0,13 0,14 7 98 45,2 4 25/10/2000 15:26:02

4 Thixo 1,43 9,77 0,998 0,11 0,12 1 108 42,7 4 25/10/2000 15:29:45

8 1 9,53 6,62 0,989 0,23 0,24 0 717 29,1 1 25/10/2000 18:02:19

2 9,05 8,79 0,983 0,33 0,35 - 2 680 38,7 1 25/10/2000 18:09:28

9 1 1,79 3,64 0,999 0,05 0,06 6 125 15,0 1 36 min 26/10/2000 09:53:42

2 1,74 3,65 0,993 0,13 0,14 6 122 15,0 1 min 26/10/2000 09:59:48

3 Thixotropy 1,81 3,83 0,995 0,11 0,12 5 128 15,6 4 min 26/10/2000 10:06:21

10 1 3,75 9,27 0,997 0,15 0,16 4 248 35,9 1 26/10/2000 11:40:45

2 3,36 10,38 0,997 0,15 0,15 6 232 41,9 1 26/10/2000 11:47:38

3 Thixo 3,69 10,62 0,996 0,18 0,19 5 253 42,0 4 26/10/2000 11:51:56

11 1 6,50 7,24 0,989 0,34 0,36 6 443 28,9 1 26/10/2000 15:11:20

2 6,77 8,86 0,986 0,42 0,45 7 509 39,0 1 26/10/2000 15:17:08

12 1 8,41 9,59 0,998 0,12 0,13 - 2 584 39,0 1 27/10/2000 10:14:02

2 9,51 10,24 0,997 0,16 0,16 - 2 669 42,1 1 27/10/2000 10:22:22

3 11,84 13,28 0,996 0,19 0,20 2 890 58,4 1 27/10/2000 10:49:33

Oil error 1 plug 7,74 10,74 0,995 0,20 0,21 - 1 528 42,9 1 27/10/2000 11:31:05
A - 88

The thixotropy was evaluated for four mixtures; Mixture #6, Mixture #7, Mixture #9 and

Mixture #10. Mixture #7 was tested twice (Na-7A and Na-7B) with almost identical results. The

thixotropic properties were evaluated by determining up and down curves (up and down refer to

the increase or decrease of the velocity). The area between the up and down curves is “the rate of

work per unit volume”; it cannot be directly characterized as a material parameter as it depends

heavily on the shear history of the material tested. The size of the “thixotropy area” should also

be related to the yield value of the material.

The “thixotropy” is lower for mixture #9 though relative to the yield value for mixture #10 is the

lowest. The “thixotropy” is significantly higher for mixture #7.

0

2

4

6

8

10

0 0,2 0,4

V e l o c i t y ( r e v / s )

N m )

Mix-06

Mix-7A

Mix-7B

Mix-09

Mix-10

Thixotropy
A - 89

Data and graphs obtained using the BTRHEOM

The dotted line represents the modified Bingham model fitted to the points.

Mix 1 

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 2 

0

0.5

1

1.5

2

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 3 

0

2

4

6

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 4 

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 5 

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 6

0

1

2

3

4

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)
A - 90

Mix 7 

0

1

2

3

4

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 8 

0

2

4

6

8

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 9 

0

1

2

3

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 10 

0

1

2

3

4

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 11 

0

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1

rotation speed (rev/s)

torque (N.m)

Mix 12 

0

2

4

6

8

10

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

rotation speed (rev/s)

torque (N.m)

first measurement

first, fitted

30 minutes later

second, fitted
A - 91

The following tables show the data points used for the graph above. The readings were

recorded by decreasing rotation speed. The concrete was vibrated prior to start of the

measurements to ensure good filling of the bucket, unless stated otherwise.

Mixture #1

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.803 9.173

2 0.687 8.623

3 0.56 8.173

4 0.457 7.57

5 0.305 7.219

6 0.219 6.676

7 0.091 6.181

Mixture #2: The concrete was not

vibrated prior to measurement.

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.795 1.763

2 0.694 1.733

3 0.553 1.739

4 0.468 1.65

5 0.319 1.608

6 0.214 1.588

7 0.095 1.447

Mixture #3.

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.806 5.209

2 0.685 4.922

3 0.568 4.495

4 0.447 4.298

5 0.325 3.783

6 0.207 3.456

7 0.106 3.014

Mixture #4

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.831 8.911

2 0.704 8.41

3 0.589 8.032

4 0.451 7.872

5 0.342 7.768

6 0.175 7.934

7 0.113 7.592

Mixture #5

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.9 9.163

2 0.776 7.784

3 0.601 7.37

4 0.47 6.644

5 0.366 6.568

6 0.229 5.989

7 0.167 6.614

Mixture #6: The concrete was not

vibrated prior to measurement.

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.803 3.118

2 0.681 2.997

3 0.575 2.933

4 0.45 2.703

5 0.331 2.463

6 0.209 2.232

7 0.095 1.834
A - 92

Mixture #7: The concrete was not

vibrated prior to measurement.

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.796 2.875

2 0.684 2.818

3 0.555 2.673

4 0.452 2.621

5 0.332 2.478

6 0.216 2.175

7 0.1 2.045

Mixture #8

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.805 7.163

2 0.678 7.045

3 0.57 6.88

4 0.433 6.677

5 0.328 6.471

6 0.217 6.329

7 0.097 6.108

Mixture 9. The concrete was not

vibrated prior to measurement.

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.807 2.634

2 0.69 2.645

3 0.576 2.594

4 0.462 2.546

5 0.326 2.437

6 0.217 2.441

7 0.095 2.203

Mixture 10

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.799 3.487

2 0.684 3.423

3 0.543 3.37

4 0.463 3.224

5 0.33 3.165

6 0.224 2.911

7 0.108 2.671

Mixture #11

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.799 4.555

2 0.694 4.519

3 0.578 4.527

4 0.458 4.344

5 0.311 4.332

6 0.219 4.267

7 0.079 4.285

Mixture #12

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.8 6.051

2 0.682 6.027

3 0.569 5.921

4 0.48 5.89

5 0.312 5.678

6 0.204 5.524

7 0.088 5.512
A - 93

Mixture #12: Second measurement (30 min after the first one)

Point Speed Torque

n° (rev/s) (N⋅m)

1 0.797 8.648

2 0.678 8.453

3 0.556 8.208

4 0.448 7.916

5 0.331 7.646

6 0.218 7.312

7 0.093 6.876

Concrete parameters calculated from the down curves

Date Mixture File

Yield

stress (Pa)

Plastic

viscosity

(Pa⋅s)

10/24/00 1 LNAC004 1619 181

10/24/00 2 LNAC005 406 18

10/24/00 3 LNAC006 771 136

10/24/00 4 LNAC008 2139 51

10/25/00 5 LNAC009B 1753 94

10/25/00 6 LNAC011 505 78

10/25/00 7 LNAC012 549 54

10/25/00 8 LNAC013 1662 67

10/26/00 9 LNAC014 624 25

10/26/00 10 LNAC016 740 50

10/26/00 11

See note

LNAC018 1189 27

10/26/00 12 LNAC020 1503 38

Note for Mixture #11: the lowest rotation speed was recorded as 0, leading to an error in

the data processing. These values were calculated later, from the raw data, with the same

equations, without the point at speed zero.
A - 94

Data and graphs obtained using the CEMAGREF-IMG

List of the various tests and comments.

Mixture

#

Text file

for the

seal

Text file

for the

concrete

Height of the

sheared concrete

sample (m)

Comments

1 Mix1a.txt Seal1a.txt 0.655

2 Mix2a.txt Seal2a.txt 0.678 Segregation at the end of the test: width 70 mm,

depth of segregation 30 mm to 70 mm

3 Mix3a.txt Seal3a.txt 0.670

4 Mix4b.txt Seal4a.txt 0.655

5 Mix5b.txt Seal5a.txt 0.345 Concrete too stiff to start the test. Part of the

concrete is removed from the rheometer. Test

restarted at T0+33 min

6 Mix6a.txt Seal6a.txt 0.655

7 Mix7a.txt Seal7a.txt 0.635 Light segregation at the end of the test: width=60

mm, depth: 10 mm

8 Mix8a.txt Seal8a.txt 0.645

9 Mix9a.txt Seal9a.txt 0.605

10 Mix10a.txt Seal10a.txt 0.675

11 Mix11a.txt Seal11a.txt 0.645

12 Mix12a.txt Seal12a.txt 0.645 A second test is performed at To+43 min.

corresponding to Mix12b.txt and Seal12a.txt. For

this test, vibration is needed to re-start the rotation,

applied with vibrating poker put in the concrete

specimen.

The measurements of the width of the sheared zone are given in Appendix C.

Direct calculation of the shear yield stress

 We have 2

c

0

2 hR

C

π

τ = so 3 c

c

0 R

hR

C

Δ

π

Δτ = and finally: 

c

c

0 0

R

R

2

Δ

Δτ = τ

The mean error on the measurement of the width of the sheared zone is estimated to be

equal to the maximum diameter of the aggregate (i.e., 1.25 time diameter 16 mm for

mixture #1 to #7, 1.25 time diameter 20 mm for mixture #8 to #11 and 1.25 time diameter

6.3 mm for mixture #12)

The following figures present the values of the shear yield stress calculated for each

mixture and for each rotation speed, with their corresponding error bar. In a perfect

experiment, all the values of calculated shear yield stress should be equal on each figure.

This was not the case so, for each mixture, the shear yield stress was calculated as the

mean of the lowest value of the tops of the error bars and the largest value of the bottoms

of the error bars. This shear yield stress is considered to be acceptable only if it is

included in all error bars. According to this procedure, we can see on the following

figures, that the values obtained for mixture #3, mixture #9 and mixture #12

(respectively: 850 Pa, 423 Pa and 1148 Pa) are not acceptable. The decrease of the

calculated shear yield stress values with the rotation speed observed with mixture #3 is

probably due to the horizontal segregation of coarse aggregate, which tends to occur

more and more during the test, because of the increase of the dead zone. Then, the

mixture-composition is assumed to change, from the inner cylinder vicinity (where the
A - 95

mixture is richer in fine elements) to the outer cylinder (where the mixture is leaner).

The tendency observed for mixture #9 and mixture #12 is not clear, and it could be due to

an error in the measurements.

No measurement was available for mixture #5, owing to the fact that the concrete top

surface was hardly visible, and for the second test with mixture #12. Only one

measurement was available for each of Mixture #1 and #4.

The sheared zone width observed on mixture #4 was low, as compared to the maximum

diameter of aggregate, even at the maximum rotation speed. Therefore, it can be assumed

that the part of the sample that was sheared during the test was more a mortar than the

concrete in bulk. Finally, the shear yield stress calculated is not an exact value but a

minimum bound of the concrete yield stress.

Yield values deduced from the width of the sheared zone and the equation 21 in

Section 3.3 (main part of this report).

Mixtur

e #

t0 (Pa)

1 1832

2 437

3 -

4 > 2138

5 -

6 487

7 410

8 1417

9 -

10 535

11 1034

12 -

12* -

*second test
A - 96

Width of the sheared zone Ec

Mixture 1

W (rad/s) Experimental Ec (mm)

0.756 35

Mixture 2

W (rad/s) Experimental Ec (mm)

0.900 50

0.600 30

0.300 20

0.100 10

Mixture 3

W (rad/s) Experimental Ec (mm)

1.700 80

1.500 80

1.200 70

0.900 60

0.600 50

0.500 50

0.300 40

0.100 30

Mixture 4

W (rad/s) Experimental Ec (mm)

1.518 10

Mixture 6

W (rad/s) Experimental Ec (mm)

1.800 130

1.500 110

1.300 110

1.000 100

0.900 100

0.700 80

0.600 80

0.400 70

0.300 50

Mixture 7

W (rad/s) Experimental Ec (mm)

2.000 140

1.700 140

1.500 130

1.200 130

1.000 120

0.800 90

0.600 60

0.300 60

0.150 20

Mixture 8

W (rad/s) Experimental Ec (mm)

1.700 40

1.500 30

1.300 20

1.000 20

0.800 20

0.500 20

0.300 5

Mixture 9

W (rad/s) Experimental Ec (mm)

2.100 110

1.700 90

1.200 50

0.900 30

0.600 25

0.300 20

0.150 15
A - 97

Mixture 10

W (rad/s) Experimental Ec (mm)

1.900 150

1.600 150

1.300 140

1.000 120

0.800 90

0.500 40

0.200 30

Mixture 11

W (rad/s) Experimental Ec (mm)

1.600 40

1.200 40

1.000 30

0.600 30

0.300 20

0.100 20

Mixture 12

W (rad/s) Experimental Ec (mm)

1.600 50

1.300 40

1.000 25

0.700 25

0.300 20
A - 98

Values of the shear yield stress calculated with Equation 21 from Section 3.3 for

different rotation speeds. The horizontal dotted lines give the value adopted for each

mixture. To be acceptable a dotted line must pass through the error bars.

Mix #1

0

500

1000

1500

2000

2500

0.0 0.2 0.4 0.6 0.8

W (rad/s)

0 (Pa)

Mix #2

0

100

200

300

400

500

600

0.0 0.5 1.0

W (rad/s)

0 (Pa)

Mix #3

0

200

400

600

800

1000

1200

1400

0.0 0.5 1.0 1.5 2.0

W (rad/s)

0 (Pa)

Mix #4

0

500

1000

1500

2000

2500

0.0 0.5 1.0 1.5 2.0

W (rad/s)

0 (Pa)
A - 99

Mix #6

0

100200300400500600700

0.0 0.5 1.0 1.5 2.0 W (rad/s)

0 (Pa)

Mix #7

0

100

200

300

400

500

0.0 1.0 2.0 3.0

W (rad/s)

0 (Pa)

Mix #8

0

500

1000

1500

2000

0.0 0.5 1.0 1.5 2.0

W (rad/s)

0 (Pa)

Mix #9

0

100

200

300

400

500

600

0.0 1.0 2.0 3.0

W (rad/s)

0 (Pa)

Mix #10

0

100

200

300

400

500

600

700

800

0.0 0.5 1.0 1.5 2.0

W (rad/s)

0 (Pa)

Mix #11

0

200

400

600

800

1000

1200

1400

0.0 0.5 1.0 1.5 2.0

W (rad/s)

0 (Pa)

Mix #12

0

200

400

600

800

1000

1200

1400

0.0 0.5 1.0 1.5 2.0

W (rad/s)

0 (Pa)
A - 100

Fitting of the curves for torque vs. rotation speed obtained for the seals

The following table summarizes the data concerning the fitting of the experimental

curves obtained for the seals alone. Figures of these curves can be found below.

Curve fitting for measurements on the seal alone

Mixture

#

Equation Mean error Range of fit

(N×m) Wmax (rad/s) Wmin (rad/s)

1 Cseal=135.3 + 17.89 Ω 8.3 1.889 0.1

2 Cseal=68.9 + 3.02 Ω 11.3 2.017 0.1

3 Cseal=93.1 + 3.59 Ω 8.8 2.129 0.1

4 Cseal=114.5 + 0.71 Ω 7.9 2.052 0.1

5 Cseal=162.6 -3.49 Ω 18.7 2.300 0.1

6 Cseal=119.8 + 6.49 Ω 5.1 2.039 0.1

7 Cseal=128 + 4.06 Ω 7.7 1.987 0.1

8 Cseal=133.9 + 4.65 Ω 4.6 1.872 0.1

9 Cseal=143.4 + 3.09 Ω 7.3 2.067 0.1

10 Cseal=140.4 + 7.59 Ω 4.5 1.898 0.1

11 Cseal=131.6 -2.49 Ω 5.4 1.635 0.1

12 Cseal=151.8 + 5.08 Ω 5.7 1.956 0.1

12* Cseal=151.8 + 5.08 Ω 5.7 1.956 0.1

*second test

Analysis with the Bingham model

The results are summarized in the table below. Figures of these curves can be found

below under “Experimental and fitted torque-rotation speed curves”. It can be seen that,

for some mixtures, the τ0 values calculated with the Bingham model are significantly

different from the values calculated directly. This means that even if the inner cylinder of

the CEMAGREF-IMG rheometer is equipped with a metallic grid, a significant slippage

occurs between the cylinder and some concretes. This phenomenon may be related to a

horizontal segregation, where coarse particles are expelled from the sheared zone, so that

shear tends to be concentrated in a thin annulus around the rotating cylinder, where the

material is more fluid than in the rest of the sample.
A - 101

Results according the Bingham model

Mixture

#

t0 (Pa) μ (Pa s) Mean error

max

&g Range of fit

 (N×m) (1/s) Wmax (rad/s) Wmin (rad/s)

1 1027 253 23.6 5.4 1.057 0.1

2 463 3 11.6 40.8 1.936 0.1

3 576 124 20.2 9.1 1.817 0.1

4 1282 82 27.0 13.1 1.519 0.1

5 848 125 15.2 10.4 1.677 0.1

6 384 63 14.7 10.3 1.838 0.1

7 356 43 13.9 12.6 2.053 0.1

8 1129 42 8.3 16.8 1.741 0.1

9 504 3 5.8 46.6 2.131 0.1

10 504 43 10.9 13.5 2.021 0.1

11 967 21 8.1 20.7 1.834 0.1

12 929 47 9.4 16.5 1.971 0.1

12* 1252 105 24.5 12.1 1.651 0.1

*second test

Summary

The table below summarizes the values of τ0 calculated with the Bingham model and

from the width of the sheared zone Ec. When the difference is high, slippage has probably

occurred between the inner cylinder and the concrete sample. In this case, the rheological

parameters calculated with the Bingham model are not valid and should not be

considered.

The figure on page A-102 shows the differences observed between the two methods as a

function of the slump. It appears that for slump lower than approximately 110 mm,

slippage occurs, as in mixture #5 and 12. Again in this case, the rheological parameters

evaluated with Bingham model are not valid and cannot be used for these tests.

According to “Direct calculation of the shear yield stress” (page A-94), mixture #3 was

certainly subject to segregation and rheological parameters are probably not relevant.

Mixture #9 and #12 (for the first test) were probably not subject to slippage because their

slumps were respectively 232 mm and 150 mm; moreover, the shear yield stress

calculated with the Bingham model is close to the one calculated with Ec. Therefore, even

if the direct measurement of the shear yield stress was subject to errors in measurement,

the rheological values calculated with Bingham can be accepted.
A - 102

Comparisons of shear yield stresses calculated directly from Ec and with the

Bingham model assuming no slippage

Mixture

#

t0 calculated with

Bingham (Pa)

t0 calculated from

Ec (Pa)

Difference (Pa) Slump (cm)

1 1027 1832 805 9.7

2 463 437 25 22.5

3 576 - - 18.7

4 1282 >2138 >856 9

5 848 - - 10.5

6 384 487 103 22.7

7 356 410 55 23.2

8 1129 1417 289 12.8

9 504 - - 23.2

10 504 535 32 22.2

11 967 1034 67 13.2

12 929 - - 15

12* 1252 - - 10.3

* second test

0

100

200

300

400

500

600

700

800

900

0 10 20 30

Slump (cm)

Observed difference (Pa)

Difference between the shear yield stress calculated with Equation 21 or Equation

28 (see Section 3.3) and the slump

Finally, the only reliable rheological values for use in comparing the different rheometers

are summarized in the table below.
A - 103

Rheological values judged to be reliable

Mixture

#

t0 calculated with

Ec (Pa)

t0 calculated with

Bingham (Pa )

μ calculated with

Bingham (Pa s)

1 1832 - -

2 437 - 3

3 - - -

4 >2138 - -

5 - - -

6 487 - 63

7 410 - 43

8 1417 - -

9 - 504 3

10 535 - 43

11 1034 - 21

12 - 929 47

12* - - -

* second test

For further investigations with the CEMAGREF-IMG rheometer, it is proposed to fix

blades on the surface of the inner cylinder to avoid slippage.
A - 104

Experimental and fitted torque-rotation speed curves

C seal: torque applied to the seal alone

Net torque: is torque really applied to the concrete sample

MIXTURE 1

Seal1a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

180

200

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix1a.txt

800

900

1000

1100

1200

1300

1400

1500

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3)
A - 105

MIXTURE 2

Seal 2a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

180

200

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix2a.txt

0

5 0

100

150

200

250

300

350

400

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 106

MIXTURE 3

Seal 3a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

180

200

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix3a.txt

400

500

600

700

800

900

1000

1100

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 107

MIXTURE 4

Seal4a.txt

0

20

40

60

80

100

120

140

160

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix4b.txt

800

900

1000

1100

1200

1300

1400

1500

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 108

MIXTURE 5

Seal5a.txt

0

50

100

150

200

250

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix5b.txt

0

100

200

300

400

500

600

700

800

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 109

MIXTURE 6

Seal6a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix6a.txt

0

100

200

300

400

500

600

700

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 110

MIXTURE 7

Seal7a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

180

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix7a.txt

0

100

200

300

400

500

600

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve (see Equation 28 and equation 29 in Section

3.3).
A - 111

MIXTURE 8

Seal8a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix8a.txt

600

700

800

900

1000

1100

1200

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 112

MIXTURE 9

Seal9a.txt

0

20

40

60

80

100

120

140

160

180

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix9a.txt

0

5 0

100

150

200

250

300

350

400

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 113

MIXTURE 10

Seal10a.txt

0

20

40

60

80

100

120

140

160

180

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix10a.txt

0

100

200

300

400

500

600

700

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 114

MIXTURE 11

Seal11a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix11a.txt

0

100

200

300

400

500

600

700

800

900

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 115

MIXTURE 12

Seal12a.txt

0

20

40

60

80

100

120

140

160

180

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix12a.txt

400

500

600

700

800

900

1000

1100

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).

MIXTURE 12 (second test)
A - 116

Seal12a.txt

0

2 0

4 0

6 0

8 0

100

120

140

160

180

0.0 0.5 1.0 1.5 2.0 2.5

Rotation speed (rad/s)

Torque Cseal (Nm)

Mix12b.txt

800

900

1000

1100

1200

1300

1400

1500

1600

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Rotation speed (rad/s)

Net torque C (Nm)

Legend

 + Experimental values 3⁄43⁄4- Curve fitting (see Equation 28 and equation 29 in

Section 3.3).
A - 117

Data and graphs obtained using the IBB

The dotted line represents the modified Bingham model fitted to the points.

Mix 1

y = 0,068x - 0,736

R

2

 = 0,960

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25 30

Torque (Nm)

Speed (rev/s)

Mix 2

y = 0,187x - 0,064

R

2

 = 0,967

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 3

y = 0,076x - 0,277

R

2

 = 0,986

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 4

y = 0,086x - 0,638

R

2

 = 0,941

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 5

y = 0,068x - 0,268

R

2

 = 0,898

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 6

y = 0,097x - 0,174

R

2

 = 0,961

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 7

y = 0,107x - 0,092

R

2

 = 0,955

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 8

y = 0,113x - 0,645

R

2

 = 0,973

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)
A - 118

Mix 9

y = 0,165x - 0,156

R

2

 = 0,978

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 10

y = 0,113x - 0,223

R

2

 = 0,967

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 11

y = 0,152x - 0,603

R

2

 = 0,896

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 12

y = 0,110x - 0,688

R

2

 = 0,981

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)

Mix 12b

y = 0,081x - 0,651

R

2

 = 0,935

0

0,2

0,4

0,6

0,8

1

0 5 10 15 20 25

Torque (Nm)

Speed (rev/s)
A - 119

The following tables show the data points used for the graphs above. The readings

were recorded by decreasing rotation speed. The data used for calculations are from

Point 1 (Point 0 is excluded) to Point 6 included. The speeds equal to 0 are not taken into

account for calculations.

For each mixture the following parameters were used:

H = Yield stress; G = Viscosity; R2 = correlation factor;

M and B are parameters to calculate the yield stress and viscosity

Mixture #1: Parameters values are:

H = 14.722; G = 10.842; R2 = 0.96;

M = 0.068; B = -0.736

Point

#

Torque

N m

Speed

Rev/s

0 26.098 0.979

1 25.02 0.931

2 20.918 0.778

3 20.808 0.626

4 17.3 0.477

5 16.223 0.334

6 13.925 0.193

7 4.222 0

8 4.04 0

Mixture #2: Parameters values are:

H = 5.345; G = 0.341; R2 = 0.966;

M = 0.187; B = -0.064

Point

#

Torque

N m

Speed

Rev/s

0 6.255 0.984

1 5.535 0.937

2 4.514 0.782

3 3.447 0.629

4 2.565 0.479

5 2.15 0.336

6 1.778 0.195

7 0.522 0

8 0.289 0

Mixture #3: Parameters values are:

H = 13.207; G = 3.669; R2 = 0.986;

M = 0.076; B = -0.278

Point

#

Torque

N m

Speed

Rev/s

0 17.777 0.97

1 15.824 0.925

2 14.319 0.77

3 11.447 0.62

4 9.305 0.471

5 8.263 0.328

6 6.487 0.191

7 1.571 0

8 1.058 0

Mixture #4: Parameters values are:

H = 11.656; G = 7.438; R2 = 0.941;

M = 0.086; B = -0.638

Point

#

Torque

N m

Speed

Rev/s

0 19.531 0.969

1 18.547 0.924

2 15.629 0.768

3 15.193 0.62

4 11.867 0.469

5 11.142 0.324

6 10.634 0.189

7 4.464 0

8 4.81 0
A - 120

Mixture #5: Parameters values are:

H = 14.612; G = 3.915; R2 = 0.898;

M = 0.068; B = -0.268

Point

#

Torque

N m

Speed

Rev/s

0 21.627 0.978

1 17.891 0.93

2 15.334 0.779

3 10.834 0.626

4 10.45 0.479

5 10.354 0.334

6 7.462 0.195

7 4.327 0

8 4.04 0

Mixture #6: Parameters values are:

H = 10.314; G = 1.8; R2 = 0.961;

M = 0.097; B = -0.174

Point

#

Torque

N m

Speed

Rev/s

0 14.375 0.977

1 11.748 0.927

2 9.675 0.774

3 7.469 0.622

4 6.686 0.474

5 4.822 0.329

6 4.61 0.191

7 0.763 0

8 0.962 0

Mixture #7: Parameters values are:

H = 9.311; G = 0.856; R2 = 0.955;

M = 0.107; B = -0.092

Point

#

Torque

N m

Speed

Rev/s

0 11.378 0.975

1 9.906 0.926

2 7.332 0.774

3 6.684 0.624

4 5.3 0.473

5 3.434 0.329

6 3.348 0.19

7 0.541 0

8 0.192 0

Mixture #8: Parameters values are:

H = 8.846; G = 5.71; R2 = 0.973;

M = 0.113; B = -0.645

Point

#

Torque

N m

Speed

Rev/s

0 16.26 0.974

1 13.58 0.923

2 12.853 0.772

3 10.917 0.621

4 9.833 0.473

5 9.247 0.326

6 7.064 0.189

7 3.208 0

8 3.559 0

Mixture #9: Parameters values are:

H = 6.062; G = 0.948; R2 = 0.978;

M = 0.165; B = -0.156

Point

#

Torque

N m

Speed

Rev/s

0 7.057 0.989

1 6.559 0.94

2 5.951 0.785

3 4.339 0.633

4 4.032 0.484

5 3.142 0.338

6 2.132 0.197

7 0.966 0

8 0.577 0

Mixture #10: Parameters values are:

H = 8.883; G = 1.982; R2 = 0.967;

M = 0.113; B = -0.223

Point

#

Torque

N m

Speed

Rev/s

0 11.695 0.984

1 10.053 0.934

2 9.244 0.781

3 7.04 0.629

4 6.208 0.478

5 5.669 0.335

6 3.455 0.195

7 1.019 0

8 1.443 0
A - 121

Mixture #11: Parameters values are:

H = 6.568; G = 3.959; R2 = 0.896;

M = 0.152; B = -0.603

Point

#

Torque

N m

Speed

Rev/s

0 12.497 0.975

1 9.985 0.926

2 9.168 0.773

3 7.314 0.62

4 7.375 0.472

5 5.555 0.327

6 6.084 0.189

7 3.127 0

8 2.982 0

Mixture #12: Parameters values are:

H = 9.074; G = 6.237; R2 = 0.98;

M = 0.11; B = -0.687

Point

#

Torque

N m

Speed

Rev/s

0 15.703 0.98

1 14.563 0.933

2 13.309 0.779

3 11.814 0.629

4 11.123 0.479

5 8.77 0.333

6 8.206 0.194

7 2.819 0

8 2.694 0

Mixture #12b: Parameters values are:

H = 12.359; G = 8.049; R2 = 0.935;

M = 0.081; B = -0.651

Point

#

Torque

N m

Speed

Rev/s

0 19.739 0.978

1 18.056 0.928

2 18.141 0.774

3 16.892 0.622

4 13.809 0.473

5 12.019 0.329

6 10.366 0.192

7 4.362 0

8 4.137 0

Summary of the values

calculated from the

measurement with the IBB

Mixture

#

Plastic

Viscosity

Yield

stress

Nms Nm

1 14.722 10.842

2 5.345 0.341

3 13.207 3.669

4 11.656 7.438

5 14.612 3.915

6 10.314 1.8

7 9.311 0.856

8 8.846 5.71

9 6.062 0.948

10 8.883 1.982

11 6.568 3.959

12 9.074 6.237
A - 122

Data and graphs obtained using the Two-Point test

Details of the analysis are included in Section 3.5 of the main part of this report.

Mix 1

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 2

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 3

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 4

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 5

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 6

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5 6

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)
A - 123

Mix 7

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 8

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 9

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 10

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 11

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)

Mix 12

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5

speed (volts)

oil pressure (volts)

concrete

idling (before)

idling (after)
A - 124

Summary of the results calculated from the figures above. Details of the

calculations are given in Section 3.5 of the main part of this report.

regression analysis output: oil pressure vs speed (voltages) Bingham constants

idling concrete (after correction) test

number

intercept slope R

2

intercept slope R

2

g

(Nm)

h

(Nms)

yield

stress

(Pa)

plastic

viscosity

(Pa.s)

1 0.060 0.049 0.946 0.256 0.068 0.962 7.53 3.51 919 61

2 0.064 0.047 0.934 0.081 0.051 0.985 0.65 0.74 80 13

3 0.082 0.045 0.915 0.149 0.071 0.974 2.57 4.80 314 83

4 0.077 0.047 0.924 0.303 0.046 0.937 8.68 - 1059 -

5 0.066 0.056 0.944 0.215 0.060 0.958 5.73 1.11 698 19

6 0.077 0.044 0.934 0.108 0.057 0.974 1.19 2.40 145 41

7 0.064 0.048 0.940 0.085 0.060 0.990 0.81 2.22 98 38

8 0.081 0.06 0.943 0.228 0.053 0.967 5.65 1.29 689 22

9 0.061 0.048 0.936 0.095 0.054 0.983 1.31 1.11 159 19

10 0.054 0.054 0.940 0.108 0.060 0.985 2.07 1.11 253 19

11 0.070 0.047 0.932 0.180 0.052 0.965 4.23 0.92 516 16

12 0.062 0.050 0.936 0.174 0.057 0.982 4.30 1.29 525 22

Notes:

• Mixture 4 - plastic viscosity not measurable due to low slump, yield value should be

treated with caution

• Mixtures 3, 5, 6 - idling data from single test only (others mean of two tests)
A - 125

Appendix D: Calibration report for the CEMAGREF-IMG

Acquisition system calibration
A - 126

Speed-meter calibration
A - 127
A - 128
A - 129

Torque cells calibration
A - 130

Calibration des capteur de couple du rhéomètre CEMAGREF

Constat métrologique n° 00776-2000

Capteur 1 Capteur 1

C(Nm) Tension (V) C(Nm) V

0 0 0 0

580 0.581 580 0.582

1160 1.16 1160 1.161

1740 1.741 1740 1.738

2320 2.32 2320 2.317

2900 2.907 2900 2.902

2320 2.319 2320 2.313

1740 1.74 1740 1.732

1160 1.161 1160 1.151

580 0.576 580 0.58

0 -0.005 0 0

0 0 0 0

580 0.582 580 0.584

1160 1.161 1160 1.163

1740 1.742 1740 1.74

2320 2.322 2320 2.32

2900 2.908 2900 2.904

2320 2.32 2320 2.315

1740 1.741 1740 1.734

1160 1.16 1160 1.153

580 0.58 580 0.576

0 0 0 -0.005

0 0 0 0

580 0.582 580 0.585

1160 1.162 1160 1.166

1740 1.742 1740 1.744

2320 2.322 2320 2.323

2900 2.908 2900 2.908

2320 2.323 2320 2.32

1740 1.741 1740 1.738

1160 1.16 1160 1.156

580 0.582 580 0.579

0 0 0 0.001

Capteur 1

y = 998.84x

0

500

1000

1500

2000

2500

3000

3500

0 1 2 3 4

Tension (V)

Couple (Nm)

Capteur 2

y = 1000.2x

0

500

1000

1500

2000

2500

3000

3500

0 1 2 3 4

Tension (V)

Couple (Nm)
A - 131

Appendix E: Calculation of the Kendall coefficient of concordance

Outline of the procedure for calculating Kendall’s coefficient of concordance, W

(summarized from Ref. [1]).

n objects have been ordered according to p criteria :

Object

Criterion

1 2 n

1 r11 r21 rn1

2 r12 r22 rn2

p r1p r2p rnp

sum r1. r2. rn. r..

rij is the rank ofan object i according to criterion (apparatus) j. In our case, the objects are

the mixtures and the criteria the rheometers.

For each line of the table, the sum of the terms is 

2

n(n +1)

. Then 

2

( + 1)

=

n n

rij p .

If all the rankings are identical, all the terms in a given column are equal, and the ri. are

equal to p, 2p, 3p....

The following parameter is used : ∑== −

n

i

ij

i

n

r

S r

1

2

.

( ) . If all the rankings are identical, S is

maximum, and 

12

p (n n)

S S

2 3

max

−

= = . Kendall’s W parameter is 

p (n n)

12S W 2 3

−

= , and

0 ≤ W ≤1.

The hypothesis tested here is that the p rankings are independent. The critical value of W

(at 95% confidence level) are given in a reference table (not given here) for different n

and p. If the calculated value of W is higher than the reference value, the hypothesis is

rejected, i.e., the rankings are not independent.
A - 132
A - 133

Appendix F: Artifacts in Rheological Measurements

This appendix deals with some problems related to the granular nature of fresh concrete.

They are not addressed in classical fluid rheology, and they may aid in interpretation of

rheometric measurements dealing with concrete.

Size of tested specimen

Concrete is a heterogeneous material. For making significant measurements of any of its

material properties, it is essential:

- to minimize the risk of spatial segregation; This has been done in the present program

by designing mixtures with continuous grading size and sufficient fine particle

proportions, and by taking precautions such as careful transport and re-mixing before

sampling. The absence of segregation has been checked by a number of fresh

concrete analyses (see Chapter 2);

- to test specimens, the sizes of which are large compared to the largest dimension of

heterogeneity. Here, this dimension is taken as the maximum size of aggregate

(MSA).

Assuming that a ratio of 10 between test specimen and MSA is acceptable, and taking a

MSA of 20 mm, this would lead to a cube having a 200 mm length, which makes a

volume of 8 L. However, there is not any clear threshold in this respect: the bigger the

specimen, the closer the measurement is to the ‘real’ value. On the contrary, the smaller

the specimen, the lower the correlation between the apparent and real properties.

Let us also note that it is the volume of sheared concrete that matters, not the total

volume of concrete contained in the apparatus.

Slip at the boundaries of the specimen

All methods used to deduce ‘basic’ rheological parameters from bulk measurements in

rheometers implicitly assume that the velocity gradient in the tested specimen is

continuous up to the interface. This means that the velocity between two parallel, plane

surfaces is supposed to vary linearly with distance between the surfaces. This assumption

is correct for a Newtonian liquid like some oil and water, at least for low Reynolds

numbers.

Figure F-1: Velocity gradient in a sheared layer. A) without slip; B) with slip, at low

rate; C) with slip, at high rate.
A - 134

However, with granular suspensions like fresh concrete, a interfacial layer forms

spontaneously in the vicinity of the wall, owing to the exclusion of coarse particles,

which makes the material locally more fluid than the bulk of the suspension. From a

macroscopic viewpoint, everything happens as if the strain rate was concentrated in this

limit layer, creating a sliding motion. This phenomenon is well known in concrete

pumping technology [2]. Various authors [2, 3, 4, 5] have proposed the following model

to describe this phenomenon:

i g

.v t = t0, +h (F- 1 )

where τ is the shear stress, t0,i is the interfacial yield stress, h is the interfacial viscous

constant and vg the sliding velocity. Of course, t0,i is always smaller than the concrete

yield stress t0. This means that when a shear force is applied to the material by the wall,

there is first a sliding motion (with no shear in the bulk of the concrete specimen).

Concrete starts to shear only when the shear stress t attains the yield stress, which means

that the sliding velocity is high enough (see Figure F-1).

Applying this concept to the basic rheometric problem, let us assume that an ideal

‘Couette’ coaxial viscometer is used, with e being the gap between the cylinders, and R

the mean radius and the ratio e/R << 1. With a conventional Bingham material, and no

slip at the interface, the analysis of the test is performed as follows:

t = t + μ g&

0

(F- 2 )

e

Ω R

g& = (F- 3 )

p R h t

2 Γ = 2 (F- 4 )













= + Ω

Γ

e

R

μ

R h

2 0

2

t

p

(F- 5 )

where

- G is the torque (in N⋅m);

- h is the height of the specimen (in m);

- μ is the concrete plastic viscosity (in Pa⋅s); and

- W the relative angular speed (in rad/s)between the two cylinders.
A - 135

To deduce the basic parameters t0 and μ from the macroscopic measurements, the

strategy is to plot the ratio 

R h

2

2p

Γ

 as a function of Ω

e

R

, then to identify the yield

stress with the intercept and the plastic viscosity with the slope of the obtained straight

line.

Now, let suppose that a slip, described by Equation F-1, to take place at the exterior

interface. When the slip velocity is high enough, the relationship between the torque and

the angular speed is still linear, and we have:

e

R v Ω − g

g& = (F- 6 )

i g

g

v

e

R v

t t μ = t +h

Ω −

= 0 + 0,(F- 7 )

which gives finally, when the concrete specimen is sheared:













= + Ω

Γ

e

R

μ

R h

ap ap..

2 0

2

t

p

( F-8 )

where

i

ap

μ e

μ e

μ e

0 0,

.

0

/

/

/

t

h

t

h

h

t

+

+

+

= is the apparent yield stress, and

μ

μ e

μ

ap

h

h

+

=

/

.

is the apparent plastic viscosity.

To assess the significance of this artifact, we will refer to the thesis of Kaplan [2], who

measured the four needed parameters t0, μ, t0,i and h for a variety of 37 mixtures. Taking

arbitrarily a value of 100 mm for e, mean values of 0.47 and 0.39 are found for the ratios

t0

ap.

/t0 and μ

ap./μ, respectively. It means that for a coaxial viscometer having a mean

distance of 100 mm between inner and outer cylinder, and no roughness to avoid slippage

on the external wall, an error of more than 50 % can occur in the experimental

assessment of Bingham parameters.
A - 136

Figure F-2: Rate field in the gap of the viscometer. A) with no slip; B) with slip at

the outer wall.

Wall effect

In a dry packing of particles, it is well known that the porosity tends to increase when the

distance between walls decreases. This is due to the supplementary porosity appearing at

the interface between grains and walls. Since the wall has no curvature, the volume of

individual voids is greater when a border surface of these voids is constituted by the wall

of the container (see Figure F-3). In other words, the porosity is higher near a wall.

v

d

d/2

Vp

 Figure F-3: Wall effect in a dry packing of particles. In the perturbed interfacial

volume Vp, porosity is higher than in the bulk of the specimen [6].

Such an effect also takes place in granular suspensions. During the research devoted to

self-compacting concrete rheometry [7], tests were carried out where the height of the

sheared specimen was changed (see Figure F-4). In this set-up, a supplementary blade

system was added to the original ones, the height of which could be adjusted.

Ω R

vg

Ω R
A - 137

upperblade

rotatingpart

lowerblade

fixedbowl

rheometeraxis

sheared

zone

supplementary

upperblade

Figure F-4: Modification of BTRHEOM rheometer, to display wall effect in

rheometric measurements.

A grid was fixed on the top of intermediate blades (see Figure F-5) and a piece of plastic

was added to fill the space under the bottom blades to limit the dead zones to the

interstices of the blades. So the tests could be considered as confined tests.

In the first series of tests, confined tests were performed on mixtures having a maximum

aggregate size of 16 mm. The effect of interblade distance and coarse/fine aggregate ratio

(G/S) on the apparent Bingham constants was investigated. Test results are displayed in

Figure F-6. It can be seen that strong perturbations take place as soon as the ratio between

interblade distance and maximum size of aggregate is less than four. As a general trend,

apparent rheological parameters tend to increase with the wall effect. This could be

anticipated, since the porosity of the mixture tends to grow, while the water dosage

remains constant. The higher the aggregate content in the mixture, the more pronounced

the wall effect.
A - 138

Figure F-5: Confining grid. A door can be seen on the “south-west” part of the

wheel, through which concrete could be poured into the test zone [6].

0

500

1000

1500

2000

2500

2 4 6 8

Inter-blade distance/Dmax ratio

Shear yield stress (Pa)

G/S=0,75

G/S=1

G/S=1,3

G/S=1,5

0

200

400

600

800

1000

1200

2 4 6 8

Inter-blade distance/Dmax ratio

Plastic viscosity (Pa s)

G/S=0,75

G/S=1

G/S=1,3

G/S=1,5

Figure F-6: Confined tests performed on a series of mixtures, with various

interblade distances and coarse/fine aggregate ratios [6].

In a second series [7] of confined tests, a self-compacting mixture with a maximum size

of 12.5 mm was tested in this set-up. The yield stress still tended to increase while the

plastic viscosity decreased with the wall effect (see Figure F-7). This could be attributed

to the ease of accumulation of coarse aggregates in the voids of the blades (since the

mixture was not originally saturated in coarse aggregate).
A - 139

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7 8 9 1 0

Inter- blades distance/Dmax ratio 

Shear yield stress (Pa s)

0

5 0

100

150

200

250

0 1 2 3 4 5 6 7 8 9 1 0

Inter- blades distance/Dmax ratio 

Plastic viscosity (Pa s)

Figure F-7: Confined tests performed on a self-compacting mixture.

This assumption was confirmed by a third test series [7] shown in Figure F-8. Here a

concrete having an maximum aggregate size of 25 mm is tested. Black dots deal with

confined tests, while white dots deal with unconfined tests. For unconfined tests, the

plastic piece under the bottom blades was removed in order to increase the dead zone

volume and consequently to facilitate the coarse aggregate segregation. The confined

tests were difficult to perform; sometimes, blockage occured since the interblade

distance/MSA was between 2 and 3 (“bridging effect” due to coarse aggregates). On the

other hand, unconfined tests went smoothly, but a significant decrease in apparent

Bingham parameters (especially yield stress) took place when the interblade distance

decreased. This could be due to the migration of coarse aggregate into the dead zone, so

that the material in the sheared zone became a kind of mortar.

200

400

600

800

1000

1200

1400

0 5 1 0

Inter-blades distance (cm)

Shear yield stress (Pa)

200

220

240

260

280

300

320

340

360

380

400

0 5 1 0

Inter-blades distance (cm)

Plastic viscosity (Pa s)

Figure 8: Effect of confinement on apparent Bingham constants. Black dots:

confined tests; white dots: unconfined tests.

As a tentative conclusion, we may state that:
A - 140

- as soon as the distance between blades is less than four to five times the maximum

size of aggregate, perturbations of the apparent Bingham parameters take place in the

rheometer;

- if concrete is confined in the sheared zone, both apparent yield stress and the apparent

plastic viscosity tend to be higher than the true values. Difficulties are encountered in

running the tests, owing to bridging effects;

- if coarse particles can migrate from the sheared zone to the dead zone, a significant

decrease of apparent rheological parameters may occur.

Artifacts and rheometers – A critical review

In order to judge to which extent the previous artifacts may affect the various rheometers,

some pertinent characteristics are recalled in Table F-1. In the light of the previous

considerations, the following statements are proposed:

Table F-1: Comparison between rheometers.

Rheometer Tested volume of

sheared concrete

[L]

Slip risk Minimum distance

between moving parts

[mm]

BML 5.2 Minimum 45

BTRHEOM 4.4 Minimum 100

CEMAGREF-IMG 500 Medium 220

IBB 21 High 50

Two-point 10 High 50

- The BML has a limited volume of sheared concrete. This may give a certain standard

deviation in measurements. The slip risk is minimal, owing to the fact that all limits

of sheared specimen are equipped with blades. The main critical issue lies in the

distance between blades, which is only two to three times the maximum size of

aggregate for most commercial concretes. Wall effect almost certainly plays a major

role in BML data, affecting all the sheared concrete zone. As the ratio of sheared

concrete over the total volume of specimen is low (5.2/17 = 0.31), tests can be

considered as unconfined. Therefore, some coarse aggregate migrations in dead zones

can be anticipated, giving a significant decrease in apparent Bingham constants;

- The BTRHEOM has an even more limited volume of sheared specimen, providing a

significant standard deviation of measurements. On the other hand, artifacts dealing

with slip risk and wall effect are minimal. As for the latter, the ratio between

interblade distance and maximum size of aggregate is about five. Therefore, no

significant systematic error in the determination of ‘true’ Bingham constants is

expected;

- The CEMAGREF-IMG tests a very large volume of concrete. This is the advantage

of having a ‘gigantic’ rheometer. Also, the distance between blades is more than ten

times the MSA, so that no wall effect is anticipated. Unfortunately, the roughness of
A - 141

the inner cylinder is not high enough to avoid any slippage. This fact led us to eliminate

a number of data. For the rest of the data, where the yield stress was the same

regardless of the calculation method (see Section 3.3), it can be reasonably considered

that the true rheological parameters have been quite well evaluated.

- In the IBB, the volume of concrete tested is quite high for a laboratory device. Some

wall effect may take place, although a very small volume of concrete is concerned.

On the other hand, nothing is done to prevent slippage between concrete and the

smooth inner wall. Therefore, an underestimation of Bingham constants could be

expected, if a calibration process similar to the one used for Two-Point (see Section

3.5) would be carried out. Moreover, the cross section of the impeller is lower than

the MSA. For very fluid mixtures, the impeller may shear cement paste instead of the

whole particle size range. This is why, in the fluid range of tested mixtures, IBB tends

to see Newtonian materials, instead of Bingham ones;

- For the Two-Point test, it is unlikely that the wall effect will significantly affect the

measurements, given the small volume concerned. The total volume of sheared

concrete is satisfactory with regard to statistical variability of rheological properties.

The lack of blades on the inner wall is probably the main problem. It would be

interesting to compare the results of this test with and without blades. Both horizontal

and vertical slippage would have to be prevented, given the complicated flow pattern

in this test.
A - 142
A - 143

Appendix G: Seal friction in CEMAGREF-IMG test: Effect of concrete

height

Introduction

The aim of this calculation is to find a maximum bound of the potential effect of concrete

height on the seal friction in the CEMAGREF-IMG rheometer. In the standard

calculation, and for a given rotation speed, the torque obtained with the rheometer

(almost) empty is deduced from the gross torque to calculate the torque attributable to

concrete shear. Does concrete pressure significantly affect the seal friction? If the answer

is yes, then the yield stress obtained by the standard calculation will be higher than the

‘true’ one.

Quantitative analysis

The torque generated by the seal may be written as follows:

Cseal = C0,seal + K1Ω + K 2σv( G-1 )

where σv is the vertical stress applied on the seal, Ω the rotation speed, and C0,seal, K1 and

K2 are constants depending on the lubrication given by the mortar included in the

concrete. In practice, the seal friction is evaluated with a thin layer of concrete in the

bottom of the rheometer to account for this lubrication. K1 corresponds to the ‘fluid

friction’ term, while K2 stands for the ‘solid friction’ one.

For a given concrete, the mean value of the seal friction, within the range of rotation

speeds applied during a test, can be written as following:

Cseal = C0,seal + K 2σv( G-2 )

When the rheometer is almost empty (the practical case for seal evaluation) we have:

Cseal,e = C0,seal + K2σv,e( G-3 )

with

S

Mg

σv ,e =

where

- M is the mass of the inner cylinder. Due to the high rigidity of the seal, this mass is not

supported by the motor axis but by the seal itself.

- g is the acceleration due to gravity

- S is the area of the seal in contact with the bottom of the rheometer

When the rheometer is almost full we have:
A - 144

Cseal,f = C0,seal + K2σv,f( G-4 )

with

gh

S

Mg

σv ,e = + ρc

where

− ρc is the concrete density

- h is the height of the concrete sample.

We now have

seal,e

v,e

v,f Cseal,f Cseal,e 1 C















−

σ

σ

− ≤ ( G-5 )

and

seal,e

c

seal,f seal,e C

M

hS

C C

ρ

− ≤ ( G-6 )

Numerical example:

ρc = 2300 kg/m3

h = 0.7 m

S=(π 0.76) 0.01 m2 = 0.0239 m2

M = 180 kg

The mean value of Cseal,efor all the tests made during the lab week was 133 N⋅m

Then

Cseal, f − Cseal,e ≤ 29 N ⋅m

So the maximum offset that may occur on the shear yield stress is:

2

int

0

2

29

phR

Δt ≤

where Rint is the inner cylinder radius

Rint= 0.38 m

Finally, the maximum error in the evaluation of the shear yield stress is

Δt0 ≤ 45 Pa
A - 145

Conclusion

This is the order of magnitude of the typical standard deviation for the yield stress as

measured with BTRHEOM [8]. On the other hand, the difference in absolute value

between yield stress given by CEMAGREF-IMG and BML ranges from 287 Pa to

1094 Pa. For the CEMAGREF-IMG vs. Two-Point test, the difference ranges from

312 Pa to 1079 Pa. Therefore, it is concluded that a errors in evaluating the seal friction

in the CEMAGREF-IMG test cannot explain all the discrepancy between this rheometer

and the other devices.
A - 146
A - 147

References for the Appendixes

1 G.Saporta, « Probabilités, analyse des données et statistiques ». Editions

TECHNIP, 1990 (in French)

2 KAPLAN D., “Pompage des bétons “ (Pumping of concrete), Etudes et

recherches des Laboratoires des Ponts et Chaussées, OA 36, November, available

at LCPC, 2000 (in French)

3 WEBER R., “The transport of concrete by pipeline” (translated by C. Van

Amerongen), Cement and Concrete Association Translation No. 129, 1968

4 MORINAGA M., “Pumpability of concrete and pumping pressure in pipelines”,

Fresh Concrete: Important Properties and Their Measurement, Proceedings of a

RILEM Seminar, Leeds, Vol. 7, pp. 1-39, 1973

5 BROWNE R., BAMFORTH P., “Tests to Establish Concrete Pumpability”, ACI

Journal, No. 74-19, May, 1977

6 DE LARRARD F., “Concrete Mixture-Proportioning”, Modern Concrete

Technology, No. 9, E & FN SPON, London, 421 p., 1999

7 BARBILLON C., "Influence du confinement sur les bétons autonivelants"

(Influence of the confinement on Self Compacting Concrete), Master thesis from

Ecole Normale Supérieure de Cachan, June, 1997

8 HU C., “Rhéologie des bétons fluides (Fluid concrete rheology)”, Etudes et

recherches des LPC, OA 16, published by LCPC, September, 1995